Re: 40 ESSENTIAL SNARE DRUM RUDIMENTS
So you have no idea who Bill Bachman is? Not a bad idea to look him up.
It's irrelevant how many rudiments some body picks out as 'standard'.
Bill has identified 12 motions that sum up anything one might ever run into as for hand motion (he calls them 'Gateway Rudiments'). You can create variations and blow them up to 26, 40, 44, 92, 1339, whatever. But... some of those 26/40 standard rudiments might have gotten outdated by now so for someone who's eager to address rudiments and have the maximum benefit there's no real need to stick to those - you can leave a few out and replace them by others.
BTW, I even don't know which 44 rudiments Bill picked out. They're being gradually uploaded on the site I mentioned. The 12 Gateway Rudiments are there already, plus 10 rudiments from Bill's 44 Modern Rudiments... selection. I guess many will be identical with the standard rudiments but I'm curious to see where they differ. And Bill is explaining everything thoroughly.
So... as for the app you're advertising - are there explanations on the technique used? Because simply having someone demonstrate them without any hints on how to execute them properly (least tension, maximum ergonomics) isn't enough. Better to learn just a few rudiments properly than a multifold number of them sloppily as they consist of the same _motions_. (Admittedly, combining those motions creates very different sensation/hand feel and even if you have those motions down, learning rudiments takes some time.)