You could plug in multiple signers, but it is best practice to only sign on one device at a time. Have them geographically separated or in the hands of different people. Otherwise if you bring a threshold number together, you're vulnerable to wrench attacks!

Running multiple signing sessions in parallel with different combinations of signers is an interesting idea that people have discussed to alleviate this "choice of signer problem" (it's actually not much of a problem, just a difference to existing multisig).

It does grow if you have a large group, for t-of-n,

(n-1)! / ((t-1)! * (n - t)!)

Possible combinations after the first signer.

Only 6 combinations for a 3-of-5.

But 126 combinations for a 5-of-10.