the first pair of wheels I built (48h on 20inch rims..) took me a weekend of getting angry and throwing the wheels away and picking them up later..

Just built a front wheel last friday (32h, 700c rims..) and it took me about 2 hours to dismantle the "old" wheel and rebuild it with a new rim/spokes.. In between I've probably built about 3 pairs of wheels, if that..