I'm really not that old that I've got a set routine, that I follow like a rule, and I think it has to do with what has to be done and what needs to come off, and to what extent.
When I was younger, I wasn't made to "gown", So, after the temp was over I was asked to get down to bra and panties. Since most of my standard appointments were mostly after school I would have then, and still now a skirt on, (Mom instilled the "you dress nicely with clean underwear" philosophy in me from a young age) So....
Temperature is done being taken, it was kick off the flats if I hadn't already, Skirt unbottoned and unzipped and taken off, then the ribbon or other tie; blouse was next. Socks, knee highs, thigh highs, following some reluctance, off would come the bra. Hesitancy, and hope,with a pause looking at whomever was the authority figure in the room at the moment, but the panties came off last, and never very quickly!
It really hasn't changed since adolescence. It's pretty much the same, only pants can replace skirt on ocassion. I am guessing but prior to about 11/12 I don't recall having to get completely undressed that often but when I did, it didn't seem to phase me that much.