Sorry, after nearly 6000 hours on rotary, i never experiment a engine relight in flight...
Each time i touch down before shutdown the engine.
Remenber, you need minimum 5000 ft under your seat to try the relightduring the descent : that'is is theorical...IRL, i think you need 6000 or 7000 ft...
Most of single engine helicopters flying under the limit to relight...