Probably many do that coz if they cut too early without sufficient mass they may end up being those twilight skinny guys .

Never have I heard such splendid quote ever .

Well , that's a pretty broad question. For me , i usually target my weight . In other words , i'll reach a certain weight limit then cut ,but that isn't quite effective honestly . Calculate ur needed calories for bulking , too much and u may have more fat than muscles (happened to me due to reckless and blind-less calculations , i took it for granted). Yes u will still gain fat while bulking but probably at a lower count . That's my personal experience .