Learning about the guitar on your bench can only help you.
As repairers entrusted with an object surrounded by folk lure, artistic mojo, historical relevance, personal attachment, family drama, and the weight of financial investment, it is only wise to be able to answer questions about the beauty on your bench.
AND HERE IS WHY....
Knowing about the production of an instrument will help you with your approach to the repair. Firstly, Being comfortable with the chemical compositions and technical applications used in the manufacturing of the instrument can help you analyze what happened to create the problem and how it can be fix, without just putting a band-aid on the issues. This is very true when speaking of finishes and adhesives! Your approach to deconstruction weighs heavily on knowing the manufacturer's approach to the construction- say, if you are removing a bridge, neck or binding. Knowing that the finish is lacquer could ease your mind a bit if there is some finish blushing that happens when you steam off the neck. You would know that this problem can be solved with a light buffing, or may just be flash-blushing and go away over night, or can be brushed away by applying a specific solvent. Of course, it could also tell you, if you have never worked on a guitar with lacquer, that you might be in over your head and you need to pass the job on to other repairer until you feel more comfortable.
Another example of how important it is to research the techniques and materials manufacturers use is when repairing vintage binding. Knowing that the binding is made of ivroid, or the like, can help you to save the binding by using a splicing technique, and avoid destroying it forever with superglue. Or, knowing that the company uses a cyanoacrylate adhesive to secure engineered materials together, will save you the time and embarrassment of using wood glue for the repair only to have your customer coming back in a week with a lifting bridge... or worse, another repair shop calling you to ask what you used on the repair because they have to re-do it.
Research can be a tremendous help with customer care and communication- we are in a customer service industry and need to remind ourselves of the importance of that. I am a big advocate for historical research; but let's be honest, vintage instrument research takes patience, practice and persistence. Not every instrument has a sequential serial number or manufacturer's label, and can be a real pain in the ass to track down. You might need to take note of the rosette, or the exact lettering of the logo, or the waist width or shoulder slope to really be able to identify the maker, model and year. But it's worth it. There have been numerous times, when I am evaluating a guitar for repair and I see something that isn't quite right.
The other month a vintage acoustic walks into my shop with a hair-line headstock break. The customer swears up and down that they didn't hit it on anything... a story we have all heard. As I looked over the headstock the tuning machines just seemed out-of-place. With a bit of research it was plain to see that the tuners weren't original! Nor matched the original tuning machine foot print. So I took a closer look. After removing the tuning machines to reveal no other foot prints or filled holes, indicating a retro fit, I looked even closer around the wrist of the neck and saw an ever-so-faint smile I had seen before. This was the second time the headstock had been broken and it had been refinished (luckily, that time, with the same type of finish as the rest of the guitar!). I approached the repair totally differently- I had to open up and clean out the old glue and reenforce the wood so it would break again. The customer was not the original owner, and didn't know anything of the life the guitar had before, but was quite pleased that I did.
It's rare, but I have had to tell customers that their instrument wasn't what they thought it was; e.g. it's a "Fibson" not a "Gibson".... It always breaks my heart to identify a fake- especially after the client has already purchased the instrument and has no way of returning it. But, I never mind being uncomfortable for the right reasons, and honesty is one of those reasons. I have had co-workers brush it off and say, "if it makes them feel good thinking it's a (Gibson, Fender, Martin ect.) who are you to tell them any different. Are you an expert?" No, I am not an expert, but I do a lot of research to justify experience- and for that, my customers trust me with their instruments, time and their money. And that's good for business!
I WILL CONCLUDE...
There is a rule in my shop after gaining more knowledge about an instrument: Never tell a customer what their instrument is worth. Meaning, it is never acceptable to say, "it's not worth fixing." Instead, inform them about their instrument, show them what needs done to achieve optimal playability and what that will cost, then let them decide. I have gained more customers from the run-off of other repairers's arrogance, than pennies in a wishing-well! We are here, in this world, to be problem solvers. We are here to fix things and to explain how the science and history of instruments work- Sometimes you can't see emotional value and you should be wise to respect that.