Search the thread database for Terry's video/thread called 'Cant never could' (or something like that.)
if you setup is properly tuned it should not matter one bit whether you cant, hold vertical, reverse cant, or bend over backwards. what matters is practicing in each of those positions, and more importantly, KEEPING your FORM together in all those positions. y'know, keeping the 'archers T', proper alignment, reaching full anchor every time, not torquing the bow, etc. (those are the problems mos run into when shooting at different angles.)