Don't know about Hill, as I haven't watched very many clips, but I have watched some really good shooters who don't do everything "perfect".
Take a look at Master's of the Bare Bow Vol. 1. There's a guy on there who (to my eye) has a visible collapse, every shot, and still shoots lights out. The key is "every shot". He does it the same way every time. He's got consistency down to a science.
I wouldn't presume to criticize anyone else's shooting, or say anything less than "good" form is desirable, but repeatable form is probably just as important.
Can you shoot very good with less than perfect form, as long as you're consistent? -- Yes.
Could you shoot better with very good, consistent form? -- Again, yes.
Should you strive to use good form on every shot? -- Absolutely!
After all, the more things you do right will tend to minimize small aiming errors, and the things you do wrong can't help.
That's my theory, and I'm stickin to it!
...until someone proves me wrong, anyway... :p