Hmmm yes I see what you mean now McGrath, I thought you were generalising.
BTW my post above should have read
...think of a swearword and more than likely it will start with a p, b, or d and have a short vowel... if not... a sibilant or fricative sound like s, sh or f.
that's better.
Regarding shit vs shite, I would only use the long vowel version in one phrase that I can think of, ie that used when expressing disbelief at someone else's opinion...'what a load of...' everything else gets the short vowel version including people. Maybe this is just my little idiolect though :-l