Quote Originally Posted by David Lyga View Post
This can mean more accurate development because it's easier to time 10 minutes than to time 3 minutes (because of the inflow and outflow of developer which does, and does NOT, 'count' as actual development time). With a 10 minute development time, the time needed to fill and empty the tank does not matter as much as with the 3 minute development time. - David Lyga
Bold font above added by me.

The best method for developing film is to lower the reels into an already full tank. So, a normal developing cycle would entail using three tanks, each filled with developer, stop bath, and fix (along with a possible fourth tank if you care to do a pre-wet). Obviously you need complete darkness for when the tanks are open.