I would posit that it's not about quantity, it's about quality. I ordered my custom over three years ago (it is nearing completion, though). Many things conspired to have it take this long - body shape, fingerboard width, control placement, woods, etc. - but that's OK. To me it means that there is a company where attention to detail is more important than mass production; service to the customer and making sure he/she gets exactly what she want is paramount; and that nothing is left to chance/question.
I've been to the factory and met the people who make these amazing instruments. I'd rather wait three years for a custom Alembic than have 20 off the rack instruments any day. These folks deeply care about what they do on a daily basis and it shows. I'm not saying that the mass producers don't care, but I just don't see the individual attention to detail there as I do in Alembics.
So, in summary, my custom will be worth the wait. Too many others here have seconded that. Excellence doesn't come cheap, nor does it come quickly. As they say, you get what you pay (and wait) for.
Alan