@Ryan T a good measure for A+A work is your breath. After a repeat breathe only through your nose deeply in with short pause and out short pause deeply in. After just a few repeats you recognize, that the urge to breathe will get stronger. A good sign to be ready is when your breathing is free of any urgencies. This is a way to go if you want to put serious volume of up to an hour (or more, but usually the hands have a way of saying when it's enough)
You can play the game a bit further by using Pavel's breath recommendation from S&S. As an example do five snatches and give yourself 10 breaths to recover. When this is easy reduce a breath. You come to a point where it you may not be recovered as you wish you would like how to feel to be ready. Make the recovery longer then by extending your breathing cycle. This is not easy, as it is a sure way to make resting "harder" than the ballistics.
just resting until hr drops to a certain hr margin is a very easy and convenient way to put up volume.
talk test is the poor man's way to have a rough hint where the anaerobic threshold is. This may be more useful in "pure" classic endurance events: running, biking, rowing swimming can get tricky.
You run five minutes and talk a bit. increase speed and getting to another five minute mark talk a few sentences. repeat until you eventually unable to do so. Here should be the AnT.
This test can be done with a hr monitor: increasing speed every five minutes. It takes up to 2 min where hr does not rise anymore and levels. repeat until the hr does not level, but keeps ascending. The last level hr is an indicator of AnT.
The AnT is defined where Lactate build up and breakdown are no longer in balance. Lactate keeps rising, breathing gets heavier and increases, fatigue sets in...
This AnT can be a good "safe" ceiling for "on the minute" work, as with a decent intensity recovery is incomplete pretty fast.