Seat Post Shims

Hi all,
I just wanted to get everyone's views on seat post shims? do they work? could they be used a temporary Solution?
I am currently building something new, which takes a 31.6 and I have a lovely Thomson post at 27.2 etc which I would like to use.

Is it possible?
Thanks for your help :)

Use one on my commuter/winter trainer which comes with a 31.6 and I’ve shimmed it to 27.2.

Works just fine, the seatpost does slip minimally over a few weeks to a month but I start feeling it when it has and it takes seconds to adjust

Do they work? Yes.

could they be used a temporary Solution? Yes, some manufacturers spec them as a permanent solution. Orange P7 I had came with a factory fitted (maybe glued in? I can’t remember) shim to take the obscure seattube id down to 27.2.

Should you use one in order to use your Thomson post? Given that I’ve got personal experience of a couple of Thomson posts and have heard/read of numerous more examples of specifically the 27.2mm posts being undersized then I’d say a better way to go would be to take what you would spend on a decent shim and buy a cheap post in the correct size.