Most are set to beep at 3.5v per cell. You usually want to land before that point. When it’s 200ft up and flying fairly fast you can’t always hear the beeper.
A cell checker and balancer is more useful than an alarm. You use the timer on your TX (or phone if the TX hasn’t got a timer) for planes. I fly my first pack for 4 mins, land, check the battery charge level and cell voltage with the meter, then do another minute. Rinse and repeat until you hit about 3.65-3.7v per cell and no lower than 35% charge. Set timer for 1min less than that. Then you have some capacity spare and don’t pound your lipo.
I use Hobbywing ESC’s, they come pre set to drop to 50% throttle at 3.5v so you can never get the lipo to below that without trying really hard.
I found doing the same process as FDS with starting a short flight time and checking to gauge how long to fly is good. The one thing I do different is I use the throttle% timer.
It takes a few times to dial it in good but now I can use the same timer on my race quads and my freestyle quads. As long as the pack size is the same and can fly gentle slow extended flights or I can rip a pack to shreads and kill it in 48 seconds. They come down at the exact same voltage ready to go on charge by the time I am back at the apartment at 3.7 to 3.8 volts per cell dependent on how soon I land after the timer expires.