He often does this if there are component parts he cannot get hold of. So he has to be able to make pickups with what he has in hand to take orders.
I've not yet heard of him being "full", but i know of a few winders who do.
I saw the same from UK winder 'The Creamery' which was frustrating as I fancied ordering some tapped Jaguar pickups with an unusual chrome cover (they look like Burns Tri-sonic). Nowhere else in the UK seems to sell something similar, so I'll just have to wait.
Maybe it'll save me money as I could have changed my mind by the time they are available again.
here's me thinking it was unusual, lol. Makes sense, yeah i hate waiting on stuff I ordered. i ordered a rifle years ago from a renowned english maker, Ivan Hancock, 13 week build mainly due to hand oiled stock, nearly had me busting a gut that wait, the gun was well worth it though, walnut had a sheen like glass. Blueing was deep and lustrous and had fluer de lisle engraving on the action and barrel.