Aye. As long as you do your best to learn how to become a great player in a short amount of time while playing you can be perfectly suited to maintain top-notch progress on a very lax schedual. From what I have read, a lot of people do not realise that for almost all players it's not time that is the constraining factor - it's skill.
Exactly. My guild cleared MSV after about a month of raiding, but we'd only raided every Sunday. We'd have progressed further in if scheduling didn't wipe our raid out completely (everyone was either in college or raising kids at that point).
Casual never meant less skill, it just meant not playing the game 50+hours straight...which is what old Vanilla content practically demanded of you, half of which was spent spamming for groups to do long, boring content.