How long does a bottle of ink last you?

The only colors I've bought twice are those I've dropped. I have gone through half a bottle of Pelikan turquoise in a year so that is something!

I've got a few bottles (Noodler's Black, Noodler's BBK, Pelikan 4001 Blue-Black) that are getting pretty low, but up to this point, I still haven't killed a regular bottle.

I must be the exception. I generally finish a bottle every 6-9 months. YYMV of course.

My son and I both use fountain pens. I don't exactly 3017 ink but have two bottles that we are working on. My son is in school so sometimes teachers insist he uses blue or black... So one of the bottles is blue, black or blue/black. The other bottle is something else (currently Pelikan 4001 brown). We both use relatively fine nibs so it seems like quite some time it seems like a bottle lasts between 1-2 years. I have several unopened bottles so it will be quite some time before I need to get any more ink.