I try to keep an eye on my tortoises on a daily basis, but stuff happens, torts hide, time passes... to make certain that I don't go too long without checking in with them (and in an attempt to regularize the check-ins), I made up the sheet above.
I aim to run all of my tortoises, currently six, through the health check on the first of every month (or as close to it as I can manage).
I start off by soaking them all for an hour or so, then get their weights and lengths, then inspect them from beak to tail, then give them a rubdown in the shell conditioner that I use. Make notations for each category in the checklist and jot down any areas of concerns in the "Notes" section, so that you can re-check it next month.
It's a good chance to see how they're doing, how (and if) they're growing, and keep an eye on anything I noted in the previous month's check-in. I don't worry so much about their weight so long as it doesn't drop continuously over a few months... torts grow for their entire lives, albeit very slowly once they're adults, so there should always be a slow upwards trend over time.
I check their target weight and tBMI (Tortoise Body Mass Index) every few months, which gives me a good idea about how they're doing relative to previous check-ins. The tBMI gives a nice general aim-point for their density, which can be a better measure of wellness than simple weight measurements.
A tortoise should feel heavy, like a comparably sized piece of fruit. I've had torts feel (for their size) as light as a loaf of bread and as heavy as a rock, both of which can be indicative of a problem. Comparing the tBMI every few months can give you a good idea of the general health of your tortoise(s)... they should be pretty close to 1.00, and hopefully trending towards that if over or under their ideal weight.
My forest tortoises tend to come in a bit low in their tBMI measures, and my Russians tend to come in a bit high, but knowing that, and keeping an eye on their numbers over time, helps me know that they're in generally good shape.
I find it helpful and useful and comforting to use, but you should, of course, use it only to the extent that you feel it's helping you and your torts.