For me, I'd plan on a couple hours, but it would take longer because I'd stop and talk or eat or whatever.

No matter how long I plan a trip to be, it ALWAYS takes longer. Sometimes I underestimate the distance. Sometimes I underestimate my speed. Or how long I'll talk. Or how many times I'll stop. Or getting lost. My family and I are slowing resigning ourselves to the fact that when I go on a ride, I'll never get back when I thought I would.