Sometimes you don't want to chance it with a dicky battery, a broken start solenoid, a rising tide, trouble re-starting at altitude, reluctant engine to start when hot, or a lot of reasons.
It isn't great airmanship, but sometimes you do what you gotta do. Friction up the cyclic, apply collective lock, roll down to idle, make sure disc is level, spend as little time as possible out of the cockpit.