If i log on to my google account 4 times a day for a month (120 times) do the google staff who deal with usernames know this? can the check that I have been on actively?
if i logged on just once a year, can they also do this?
basically can google find out how often you have 'logged on' to your account?

I'm sure they can tell, but I doubt they would be all that interested unless you've given them some reason why they should be.

They definitely can know if they wish to.