There are ways in which "mods" can be helpful - if you fill out dummied-out material, the way that Uristocrat came up with a list of specific densities of all the different types of stones, which were using a single default stone value for density.
Generally, however, the problem is one of organization. When something has been continuously coded for years, it becomes a serious organizational nightmare unless you have very meticulous commenting and documentation. Otherwise, it becomes problematic where one person is the only one who knows how such-and-such a piece of code works, and nobody else knows how to work well with it.
Yeah, the pauses between releases can be from a day (when it's a quickfix) to a year (when it's a lot of new mechanics and features like additions of caverns and totally new underground mechanics).
I think this one should be in the middle, from two to six months.
It's not gonna be six months. I'm guessing about a month from now.
This probably depends on how much work Toady wants to do in one release. If he wants to set up the way in which furniture is randomized inside buildings, tenants are assigned living space, putting in marketplaces, manors, rules for the way that the pinned-in backyard areas of the city have small pastures for animals, working out the way that storm sewers work, and all sorts of other potentially complex and time-consuming functions all in a single big release, it should be at least a month or two.
If he wants to push out a work-in-progress version where there is something like the bottomless food barrels, it might be in a couple weeks, followed up by fixing the bugs in the version he releases, followed up by finishing up the rest of the things he wanted to accomplish, and then more bugfixes.
Even when all this is done, "Release 2" will have the "daily activities" portion of all of this, which means that we will have all the houses and cities, and be waiting on the code that involves actually getting the humans to actually walk outside and actually
DO something in these cities, so it's not like having this release will actually be a major turning point in the game.
DF just isn't something you should keep getting impatient over every update or release, because there's ALWAYS something exciting coming over the horizon.