Being in deep Cornwall next to the sea I can confirm that unless you have a climate controlled garage your pride and joy will rot just as quick as using it every day which is why my daily has been in constant use for 14 years with no ill effects.
Average speed around here is 30 mph or zero in the summer holidays hence the motorcycle so its ideal.
I`ll probably take it to Castle Combe in a couple of weeks which is a 428 mile round trip in a day with no radio ( wouldn`t hear it anyway ) and drum brakes so I might be singing a different tune but it is an adventure or do I mean an endurance event
I have to disagree about the rusting in garages, I restored a 1962 AH Sprite in 2001, since then it has lived in the same garage for the last 17 years.
I stopped using it in 2013 and it just sat there, earlier this year I dragged it out and recommissioned it for the 60 anniversary event at Wroxall Abbey there wasn't any rust on it anywhere.
I'm in the midlands so no salt laden sea air. The problem is if you already have rust then it might keep going but if the car isn't rusty to start with a dry garage shouldn't cause any problems.