According to David Courtney you should keep your tabla in tune *and leave it there* if at all possible. He writes:
try to keep the tabla in tune. there is acommon misconception that a tabla should be loosed whenever it is not going to be played. This is only true when dealing with the poorest quality tablas, such as one might find fromBengal. Doing this for any decent tabla will make it unreliable on stage - FUNDAMENTALS OF TABLA, page 34.
It seems therefore counterproductive to tune up and then tune down your tabla, and quite possibly even more so to continuously loosen and then tighten the straps (also a bit tedious I would think!). That strikes me as possibly unnecessary trauma on the tabla head (especially on the gajara) that has to be beaten into submission on a daily basis.
Empirically speaking, the evidence I have is simply that of my own, so mileage may differ with others. One reason I have so many tablas (9 headed bayans, 3 that need reheading) is so that I can keep them exactly in tune more or less permanently (A, B, Bb, C, C#, D, Eb). I need only make the most minor tuning adjustment, if any adjustment at all. Moreover the nylon straps have helped enormously with stabilizing the tuning so that a dayan will keep exactly the same tuning for days and even weeks on end. My oldest tabla does not have nylon straps but is a very high quality tabla and has remained on 4 straps on the gatas for over 5 years and has maintained tuning at Bb +/- 15cents at the most for that many years! (admitedly it also mostly gathered dust for many years sitting there unloved and unplayed, but was none the worse for wear for that neglect!).
Moreover, there is reason for believing that a tabla, if left in tune, will actually *improve* over time. This seems to be true of my own tabla, and while the improvements may be subtle (or possibly due to the placebo effect!!) this has been dramatically the case for me for some $6 tabla skins (!) I bought back in april of this year. In fact I bought 4 of them, and like they say, you get what you pay for. Visual inspection make it immediately evident that these were inferior in craftmanship. Once put in place on my tablas, 2 of them sounded barely average but 2 of them sounded simply awful (awful enough that I scouted around for more tabla heads and discovered the amazing sound of the Mukta Das tabla heads, though there are others that are also good). In any case, 2 were beyond hope but 2 of them I decided to give a try. While it took many many weeks, and indeed several months in one case, the 2 inferior heads clear improved over time where they have become playable.
There is also something else to keep in mind. While I am admitedly speculating, if seems to me that when you first tune your tabla, no matter how accurate you are, you are very unlikely to tune it so exactly all the way around that it will be +/- 0 cents all the way around. You will invariably have a plus or minus difference of just a few cents here and there (certainly that has been my own experience). However, if you keep it in tune and you only make minor adjustments, you will discover (or at least I have discovered) that the tabla will eventually get more and more uniform all the way around insofar as tuning is concerned and from thereon only requires the lightest of touches to keep in tune with itself.
Well, that's my 2 cents worth!
Would love to hear what the experience of others has been.
My opinion given without any warranties, expressed or implied, that it's even relevant. It would be folly to rely on my opinion without seeking more professional tabla advice. If you are suffering from a tabla condition, seek immediate attention.