IMO, trying to time ammo panics is pretty dumb. Most of the panics that happen are due to unforeseen events. As many have counseled, just stockpile when it's cheap as a general rule of thumb, regardless of what timeline you might predict. Both of the most noticeable ammo scares in my time as a shooter have been unpredictable, Sandy Hook and the pandemic. I was quite glad during the pandemic that I had a nice little stash of ammo that I could fall on in the off chance that I couldn't get ammo, having of learned my lesson from Sandy Hook (I had just started really shooting a lot at that time, and was forced to make do with Freedom Munitions).
But yeah, I've been pretty happy with my TS-USA membership. The free shipping is very nice when just picking up a few boxes here or there, which happens with duty or match grade ammo for me (picking up a few boxes each time they come back in stock). The annual fee is more than evened out by the small discount I get for every order.