I think "one perfume per one occasion" is a myth -- just wear what feels right.
My only two gripes are about situations which I think call for no fragrance:
-- people wearing colognes/perfume to job interviews (which typically take place in small conference rooms -- for hours -- where a scent can be overpowering)
-- waiters wearing fragrance on the job (not that I eat out that often, but when I do I'd rather focus on my food rather than what the waiter is wearing)
Okay, rant over!