Speaking for myself as a bloke, yes, 100%. If I know stuff from a particular brand fits me well, I’m going to buy more from that brand.
100%. For a time whoever the gap shirt designers measured up for their XL size must've exactly matched my build and height, and had extra long arms the same length as mine. So it was an easy way to get a shirt that fit right, for me.
I always find it frustrating that most stores turn over their stock so often. I find a shirt I like then go back to buy another and it's gone.