Absolutely this. If we have a vehicle at a gated entry resort I always ask for an 'extra' key for the car.Unfortunately I've found that the bands are inconsistent when used for entry and pool gates. Sometimes they work but are finicky. Often times they don't work well and I resort to a room key. This is more true at security gates than pool gates. For this reason I keep a single room key in the car to use when returning to the resort to get through the security gate.
(Well...more accurately I always book at Max occupancy and then when the person at the desk asks how many keys I would like I tell them the number I need for people + 1. This avoids annoyance if plans/number of guests change and also helps if disaster strikes and a Travelex claim needs to be made).