I have read on guitar forums both yes and no. Some say it is ok to make minor neck adjustments with the truss rod to lower action, while others say no, you should shave the saddle a bit, and even others say the guitar may need a neck reset, or in the case of Taylors with the NT neck, remove or add a shim. Which is the best advice?
All of the answers are dependent upon the number of factors involved.
IF the neck as the perfect amount of relief, the ONLY proper way to lower the action is by adjusting the bridge saddle.
IF the neck has too MUCH relief, the truss rod may be tightened, thereby establishing the perfect amount of relief AND lowering the action to where it should have been in the first place. In this case, the lowering of the action happens in concert with the effect of the truss rod. Novices and hacks employ this method to 'lower' the action, but what they're actually doing is getting the neck properly adjusted. Like I said, the lower action is a byproduct.
For the purpose of answering your question: Neck resets are only appropriate when there is no longer enough saddle height at the bridge to establish a good string break angle over the saddle. The cause of this procedure is the settling of the wood in the neck, top and neck block.
Just a personal note on "other forums". I've been researching other forums and in 99.9% of the cases, it's the blind leading the deaf. There is so much wrong/stupid/hack/bullsh*t advice on those forums as to make me want to scream. It's not ALL wrong, but excavating the truth from inside the layers of conjecture, guesses and just plain old bad advice is nearly impossible. In summary: this forum dispenses nothing but the best "professional grade" solutions for its members.
BTW: I saw the pic's of your new GS Mini. It is beautiful. Nice purchase, my friend!!! ENJOY :) :)
15 years ago I would have said either yes or no to this question (depending on who was doing the talking back then). Now we adjust truss rods as an integral part of the preliminary and final action setup taking into account the geometry of the guitar.
The three points that lead us to this process are the inconsistent (from guitar to guitar) relationship between the nut position in space relative to the bridge and the middle (or tongue) of the fret board.
All these things govern a permutation of action height vs fretboard relief and we use a combination to get the string path/elipse related to these variables. For instance, and ist's only one instance : there is a point on a fingerboard where string angle relative to the fret becomes more important than relief and this in turn is also affected by by string gauge and this is a function of geometry. Simple stuff but usually totally ignored by the ruler and feeler gauge mob.
Other considerations are whether the string gauge is <more> or <less> prevalent in the action height or relief equation and the amount (if any) of twist in the neck and just how the string elipse will average or bias between the treble and bass side.
I guess this is not helpful if a simple answer was required but, if you clear your head of what the greater unwashed are spruiking on the internet and just think about the three dimensional geometry of the neck and what you are seeking to achieve (low action, clean playing, no choke bending, where the playing will be done (cowboy chords or in the big number frets) speed vs string dynamics, tone vs speed across the board and so on and so forth you will then be cooking reagrding becoming a fully aware luthier/tech.
I'm on the fly and I hope others can come in on top of my ramblings here with clearer directions and processes,
Answer is, like most things in life - yes, no, maybe, it depends. Sucks if you want a binary action set... Guitars are not that simple.
Action is, for my way of thinking, mostly a byproduct of the nut, the saddle and the neck. You adjust the one or the two or the all that needs adjusting. Personally, I set relief (height of the strings above the frets when you press down on fret one and fret 12 or 14 at the same time) by adjusting the truss rod as the first step. I set the relief for near as dammit zero at the 7th or 8th fret, but a little space - thickness of a hair. Then I set the nut, and finally I set the saddle. So if your neck needs adjusting and it has too much relief, then adjusting the truss rod is the correct thing to do. If you nut height is dialed in and the neck is perfect, you can then look at adjusting the saddle. The big question is - if you have the nut and the neck perfect and the saddle is already too low - then you look for why that is happening - could be body is deforming or neck joint issues. In that case, there are certain compromises you can make, or you can re-shim the neck or you can shave the bridge, or you can rebuild the bowed neck or... Possibilities are endless.
On many guitars the neck relief and high action height happened in concert with each other. Time, string gauge change, environmental change, etc. allowed the neck to pull up and raise the action as the result.
On some of these, you can adjust the rod to bring the relief down into the normal range and voila! the action has retuned to normal as well. This is a perfectly appropriate use of the rod to lower action. And proof, that for some odd reason, Murphy has left the building!
Adjusting the truss rod to lower or raise string heights is fine if the relief adjustment helps the, "situation" as well. for example if a different player is hitting it harder, they may benefit from more relief and increased string height in witch case a tweak of the rod accomplishes both.
A really great set-up for a guitar is an exercise in dealing with and eventually eliminating several variables until it gets you where you want to go.
Things that impact set-up, some of the more common ones there are others... include truss rod/relief, nut slots, and saddle (s).
The truss rod is the first thing that I address, usually and I set the relief where I think that it should be. Variable eliminated (at least for now, things can change depending on how far out the instrument was..). Next with the truss rod adjusted I do the nut slots and this eliminates the second variable and in doing so isolates the final major variable, the saddle and this is where I address the action as the others have said too.
Mind you straightening the neck with the rod, cutting the nut slots have also contributed often greatly to improving the action but we are not there yet.
Although you can impact the action with the truss rod only it's not what it's there for. Instead it's all about relief.
Lastly I address the saddle and measure action at the 12th.
When our car pulls to the right we can manipulate the air pressure in the front tires and maybe see some correction. But would not the car benefit from a wheel alignment and keeping the tires all inflated the same and to manufacturer specs? Sure and to me a truss rod is very much like this. We can impact some things with the adjustment but is it the best way forward to address action with only.... the truss rod - no.
Action can be lowered (or raised) with the rod but to me that's not what it's there for and instead a decent set-up is a combination of at least several factors, again there can be more..., and getting them to all work together in concert to get you where you want to go.
This is also why having a systematic approach to set-ups eliminating variables one by one is really helpful to how I work.