This isn't quite that type of checklist. That is all covered under the "develop gear checklist" and "packing" areas and also discussed more frequently in this forum. However, agree with you on a meta-issue that you mention. On a trip of 12+ months one may well encounter differences in seasons or climate and figuring out where/how you adjust is important. In addition, while a lot of things you bring aren't that different between a one month trip or a one year trip, one will need to anticipate additional wear or breakage of things.

I'll also note that folks seem to differ on how much they pack and determine packing lists in advance. I don't own a car so I'm pretty much on the bike every day. I also take shorter weekend or short trips often enough that I've developed a pretty good set of checklists and will often wait until Thursday to pack for a week long trip that departs over the weekend. However, for a 12+ month trip, I'm still doing a little more advance planning for my gear, particularly if the start of the trip is in a remote region.