Best Practice Use of mv_session_id and mv_pc ??

Hi Folks,

Is it still recommended for urls to have session ids and mv_pc numbers or is
recommended to completely turn them off?

I realised that we have quite a lot of links that aren't generated using the
area tag so they have no id or mv_pc, testing with cookies turned off using
chrome this does create multiple session ids, is it best practice to leave
them in the url?

TIA
Andy