>>7639221 (OP)I remember getting to that page and calling BS.
It's not like the skull couldn't follow his standard guide proportions, like
>>7639249 shows, so I think he was just being lazy and did whatever he wanted, since it was a skull and not a 'human head'.
>>7639426It can help with correctly dividing up the head to correctly place features (so breaking the horizontal eyeline into thirds for example). It can also help with perspective, since you'll need to rule out guidelines for that anyway (if you're being anal about it). There's also thumb-nailing, as it's very common to use the cross to indicate where the simplified character is looking without needing to draw in any details.
Generally though, it's a consistency thing, which is why animators use it a lot, because you don't want eyes shrinking or growing, or the features to be misplaced, moment to moment.
However, if you never need it, or outgrow it, that's fine too - I look at the Riley Method for drawing heads and think "man, how tedious", but I'm sure some people like taking away any guess work when placing features, so if it works for you that's great, whatever helps people.