IHR pension. Then new job?!

A colleague (40 with 22 years, and legacy 87 member) has informed me she is going down the IHR route.

Then said she might then start work again afterwards.

Out of curiosity. How does this work? Can she retire on a full pension (if successful), claim her police pension (again, if successful).....then get another full time job?! Will not that mean she earns more than what she was earning.

Am I missing something obvious. Wouldn't everyone try this approach. I know IHR seems to be far more common now.