Multiple services stale in raw 2.0

I have reduced the time for local checks from 40secs to 8secs and now it seems ok. Do you think is too much 8 secs? I have another server with a lots of local checks that take up to 20 secs without any issue.
Do you recommend to keep the total time for the agent under 3/4 secs? Could I have some problems if the local checks are slow and the total time for the agent is up to 20secs?

thank you