True. Sadly, I only get ice time every Wednesday from 5:30 to 7:00. Better than nothing, but I want to skate more. I guess once they feel dull-ish I'll sharpen them.
My coach recomends 30 hours on the ice as a general rule of thumb, but it depends on your blade, what you do etc. Most people find an indicator for themselves, maybe something that gives you trouble, mine is the right-outside edge (especially coming out of a three-turn). If I need to focus on it the blade needs sharpening.