Trying to optimize load I tried to prolong intervals between trigger checks to 30-60 seconds, but, I actually received an opposite result, trigger checks started to run faster. My findings are:
Trigger intervals x in range [0, 10] -> 1:1 ratio -> check every x seconds
Trigger intervals x in range (10,600] -> 1:0.1-0.01 ratio -> check every x/10-x/100 seconds with very non-regular timing (for example, if set to 600s, the check condition is done in range of 57-63 seconds; if set to 11s, it seems to be running in ~100ms interval).