No that it matters much, you can just make your trap so that it can only handle x number of mobs because of crowding.
And, from personal experience, you can go a little over the limit as long as it isn't for so long and nothing will happen, but I also believe you can't get banned for it, you will just be kicked so that the admins can kill all the mobs.

Repeated offenses of going over the limit does lead to bans.

@Jordi223b No that it matters much, you can just make your trap so that it can only handle x number of mobs because of crowding.
And, from personal experience, you can go a little over the limit as long as it isn't for so long and nothing will happen, but I also believe you can't get banned for it, you will just be kicked so that the admins can kill all the mobs.

+1. if my emen grinder dont suffocte the mobs my FPS will suffocate

@R4iscool1 I'm not asking how to do it, just proof that it works since I'm skeptical how someone could measure the number of mobs without command blocks.

You'll probably figure it out once you see the gif but he's using the entity cramming limit, nice and simple but very effective. Could expand it to a 2x1 area to fit more mobs, I think anything larger you might risk goin gover the server limit though

A more complicated method, but one that gives you full control over the number of mobs the spawner holds before they get killed is to use weighted pressure plates. I shared an example of how to do this a while ago.