Don’t know anything about cellos, but the thing to be checked apart from any obvious crack or seam coming apart, which would be visible anyway, on a violin or viola is the sound post. These sometimes can move after about The first six months or so, but to be honest if the viola still sounds ok it’s unlikely to need anything doing. The tailpiece and bridge are looked at as well to see if the tailpiece has moved up and to see if the bridge is ok. As far as I know not having the instrument checked can’t cause any damage except for maybe if all the strings were loosened at once the soundpost could possibly I suppose fall over.
As long the instrument hasn't been through big temperature or humidity changes since its last checkup, and hasn't suffered any hard impact or had all the strings loosened, there isn't much chance of major issues. (If any of the above things have happened, or if you don't know, then it's riskier to go without a checkup!)
Typically my luthier gives my viola a quick look-over when I bring my bow in for rehairing, just checking the bridge and fingerboard and looking for cracks and open seams at the most common places. I get a more thorough checkup every two or three years, but those checkups have only ever found any issues once (and it was just an open seam) in the 16 years I've had my viola.
idk how much trouble it is to visit a shop for you there and not sure if its a common practice for shops but One thing I do sometimes is buy strings from a shop.. theyll put them on while I wait for free... Both shops in my area just as part of it will check the bridge placement and sound. Maybe they do that sorta thing there? I wouldnt think its something to be overly concerned about doing though..especially if things sound and feel ok. And I usually just order strings and put them on myself. I think as long as you keep doing what you are and at least take them out of the case, tune and play regularly they should be ok.
@mouse im glad to see someone else has a weakness for instruments! sounds like a cool arsenal there.
yeah i did the name change in the fall during a horrible spell of not being able to play much. it implies that a level of proficiency was reached then lost which is part of the humor there with it.. 😉 i will say that during that time i did notice that some things i felt i had progressed with had slipped. tunes i thought i had down i had to go back over. but yeah its better now.. but due to work theres always that period ..like evryone..where practice time suffers. ill keep it as an ode to working adult late starter fiddle players! i salute you all 😃😊