Thank you notes after internship?

Hey everyone. I just finished a summer internship and was considering writing a thank you note to everyone I worked with (around 10 people). Do you think this is a good idea or over the top? I already thanked everyone on my last day but am thinking that sending a brief handwritten note would also be good. I haven't heard back regarding an offer, but of course I am doing this just to do it and not to sway my offer (which I know it would have no impact on anyway).

The other consideration I have is that I wanted to write in each note about my experience working with the person on the specific team(s) we worked on throughout the summer. For client confidentiality, would it be unwise to write out the full name of the company/client? I say this because if I were to mail the notes to the office, then if someone happened to get a hold of them before they reached the office, they would have the names to a couple of the bank's clients. Alternatively I could just drop off the notes at the office so long as the people I write thank you notes to know that I dropped them off.

Why do I even need to mention the client names in the first place? Well it's difficult to personalize each thank you note without mentioning the specific experience I had working with each person and the need to remind them of that specific team arises since of course everyone is on multiple teams.

I get the sense that not many people write thank you notes after an internship. Some do after an interview, which I think is fairly unnecessary since the note probably won't reach the interviewer until after the decision is made-but still a nice gesture. For a summer internship of 8-10 weeks, I think it's a great (though totally unnecessary in the sense of whether you get an offer or not) to send thank you notes post internship.