A +lie or the up-right angle(toe end)adjustment is supposedly to do with the correct swing plane???, even quirky players have the ability to get right angles at impact...I don't know the scientific reasons for this, but the trend seems to implicate it's to do with planes(excuse the pun).
You would have thought standard lie would be the natural starting point for most of us, but from what seen and learned from other players including tour professionals is that most use a degree of the upright adjustment.
Low handicap and professionals will tend have anything from standard to +2 upright for irons 1-9 and usually a degree less for their wegdes, few seldom have heel(-) adjustments, unless one stature is on the short side!
Then again, I wonder what Woosie is?
I'll not include putters, as this is a whole new argument and one would have to ring Scottie himself to arrange the appointment!
As to custom fit...It really depends on the player in question...
An extremely tall or short player is definitely going to need shaft length adjustments first, but if one thinks their height is within the standards of average, then there is no need to to go rushing to their nearest custom fit centre.
Grip size is a personal preference in my opinion...
I have thicker(2 tape) grips than standard. this stops the hands from getting to active through impact, but grips can also help to weight balance the club, usually woods/metals.
IMHO..The shaft is the probably the area that will either benefit or break a player... Get it wrong and you'll more bad rounds than good...Through experience I'd always put forgiveness above outright performance. I've had couple of tour players' stiff wedges(X-100DD)unbranded TM Racs. On a good day they're brilliant, but hit them even slightly wrong, they make one look very foolish..