At T1 I’ve never had to wait more than one person so I think the presence of a F counter is academic.
Ha, no definitely not academic. I waited 10 minutes ex-SIN in September. I guess YMMV, but once CX cut down their check-in presence to 4 desks it often got a line. Depends when you show up and how many DMs are on the flight. Monday morning and Friday afternoons you were guaranteed to wait. I guess 10 minutes doesn't sound bad big picture but when you're used to waltzing up you don't forget it when it happens.
Don’t lump Avios/BA into this. There are no free add-on sectors in BA - each award is priced sector by sector making transit itineraries expensive.
My poor understanding of the nuances shines through....my bad. Im pretty sure in Alaska and AA you can though, but I might be wrong there too.