"if" means inverse frequency and the unit here is minute
e.g. "if < 20" means the user has exhibited that behavior (on average) more than once per 20 minutes
so when "if < 5", then "frequency > 1/5"
so it would be higher than once per 5 minutes!
and "c" means the number of times the behavior has been exhibited so far (since the installation of the addon)
so -c > 10 -if < 20 means the user has done something at least 10 times with a frequency of higher than once per 20 minutes