I have to admit the manual is a little fuzzy...it does say every day, but then somewhere else it refers to every 10 hours. I don't find it all that easy and it's messy as well, so I've taken to greasing it every other mowing. For me that's about every 3 hours of use or so.
Every day is referring to a normal work day which is 8-10 hrs so your every 10hr schedule is fine.