Hi,
technically there is no limit on the amount of running sessions. But running sessions are a bad indicator for system load at all, as there are cases, where sessions are supposed to stay open for some time, without affecting system performance.
So you should rather focus on other indicators to measure load. And btw: AEM is not supposed to crash under severe load (unless it rans into an OOM), but it should just get slower.
kind regards,
Jörg