My T is in private practice in the UK, and is a member of the BACP and NCP, which apparently require monthly professional supervision to ensure ethical requirements are met, etc. It's not something we've ever talked about, as of yet, and she's never referred to a 'supervisor' or someone she would consult... Her insights in session are usually so dead-on I can't imagine her doing much but checking in, I don't feel like she's ever feeding someone else's opinion back at me. And, I have no idea if she has or has had therapy herself - though I think a lot of therapists do get therapy along the way to compliment their training?