I have a pretty crammed up Pro 2019 (I thought), but when I check the logs, most of the time it runs 3 flows per minute max. This is of course not the same as ‘triggers 3 flows per minute’, so it can be 30 at some times I guess, but those flows ‘die’ because of unmatched conditions. I don’t count them as ‘flows which ran’
I try to spread the load a bit, so instead of, say, ‘every 5 minutes’ I use ‘every 301 seconds’
Also I try to avoid these ‘every x [timeunit]’ flow triggers.
