| >>To me, the face-to-face with no pre-screening model just seems inefficient.|
It is absolutely inefficient, and if all you are looking at are the raw numbers of people getting alterations, then it would also probably be seen as absolutely bad. There are, however, many other factors at play, some of which various GMs have shared before in forum posts, and some of which are behind the scenes things that we really can't discuss at all.
>>The RP-with-the-alterer deal seems odd too because the sessions are a strange mix of IC and OOC. Maybe that's just me.
This is the part where I say that different people want different things out of an alteration session, even if getting an item done is really the biggest part of it for almost everyone.
Alteration sessions will always require a bit of OOC (the most common way I see is for players to give the requested alteration wording in ooc whispers while RPing 'out loud') unless it's one in which the person getting the alteration done has no say in what they get made (which can occasionally happen!), but if you're wanting an RP experience, you can have it.
Some alterer GMNPCs are more geared around people who want a bigger RP experience along with their alteration, some are more geared towards efficiency in numbers, some are set up to give players who aren't comfortable with the idea of PC helpers a chance to fiddle with their design directly with a GM, some are set up to give players who are totally clueless about alterations to the point they don't even know what they can get done a chance to have the time to work out an idea they'll love -- you get where I'm going here!
What we try our best to do is have a variety of different types, and in fact most of us who run alterers run different ones that fall into various different ways of doing things to address different player needs/preferences! Sometimes that's an explicit thing that is up front about the merchant in pretty much every interaction you'll have with them. Almodivar, for example, is always going to be slow, only take a few clients, and RP with them the entire time not only with their one alteration, but also likely about a bunch of other stuff too, including the 'consultation'. Sometimes it is something more tied to the particular list they're running right then, or even the number or preferences of the players there at the time.