Before I get started, dont' take this as being rude. If you're doing timed legs and you have to be out at the top of the hour and you're two min into your outbound leg and you have 4 min til exit, it's time to turn. It's really simple. You're doing timed legs, you can see a clock, just some common sense and basic math. There's no need for complication. You don't have to complete an entire leg/racetrack to exit a hold. Just turn when you need to and exit at the hold point.