If I were coating something important, like the mast, I would use quality products, and follow instructions, to a tee as well.
However, 2 season ago, I needed to redo my 30 year old Bomar Hatch frames (before putting new acrylic in them) and rebedding.
I cleaned all paint off with a wire wheel, then cleaned with vinigar, and sprayed them with a primer (made for aluminum, from an auto parts store).
As I wanted them black, and didn't mind a bit of texture, I sprayed them with a can of truck bedliner / auto rockpanel rubberized paint.
Time will tell, but it's been two seaons, and thye still look perfect.
I think one has to consider the project, and it's impact on the total boat.
I would put more effort and $$ into redoing hatches on a classic, 1/2 million $ yacht, than I would on my 30 year old 30'er. The rest of the boat is in decent shape, but by no means pristine. To spend mega $$ and time, on finish, would not make sense to me.