Can cats still pick up fleas at a cattery despite flea treatment?

[MyBiscuitspread]

I sometimes read "my dog picked up fleas after a visit to the groomers" or "my cat came back from the cattery with fleas".
This terrifies me and I always wonder if those pets in question weren't flea treated regularly or if it can happen despite meticulous flea treatment.
I am planning to leave my cats at a cattery for a week. Is there anything I can do to protect them other than give them their regular flea treatment?
Should I do flea treatment plus flea collar as a precaution? I have heard flea collars are useless but I'm desperate to find something that will give me peace of mind.
Will visit the cattery before booking to get an idea of how clean it is but I doubt it'll be possible to see anything...

Is it prescription flea treatment? It possibly depends on what you use. It might not stop them picking them up, but it should interrupt the life cycle to prevent an infestation.

Yes, we use credelio from the vets.

If it’s a decent cattery the clients should have to show proof of flea and worming along with vaccinations.