There are two more reasons for a low-time pilot to remain in contact with ATC all the time, even in uncontrolled airspace:
1. It's better to give the guys on the ground an opportunity to warn you if you are about to do something stupid than to actually do it and suffer the consequences. I learned this one in a harmless but embarrassing way, having busted an active military training zone. Upon landing, I was met by a grinning instructor who said the military ATC had already phoned him about me.
2. Practice your RT skills.