As long as you have a well-balanced battery, with all cells approximately equal in capability, it's easy to run without a BMS. That's how I run with the EIG cells.
If you have an old battery, or a cheaply-made one, it's more likely that you ahve some groups of cells taht will run down faster than others. Especially if you're running the pack close to it's limits (running it hard). I wouldn't run the old 18650 pack I have without a BMS, for that reason.
In those cases, without a BMS, you have to know how much less capacity you actually have than it's rated for, so you can watch taht with the CA. Also, how much less total voltage you'll end up with because of those groups being lower sooner than others.