Is hers a tract house and yours a custom house? Different climate where the weather's cooperated with hers but hasn't with yours?

If I had to guess (and it really is just a guess, lol), I'd say it probably has a lot to do with an individual builder's organizational skills/experience, how busy he is, how much of a perfectionist he and his subs are, his relationships with his subs, weather, complexity/detailing of the house/site, personality of the homeowner, and a zillion other things I haven't thought of and may never be aware of, lol.

Even tract builders can have wildly different timelines... My house was tossed up (far too quickly) in less than 4 months. Another poster here on the forums, who also built a production home but used a different builder, waited 7+ months for her house. I made the mistake of hoping my house would also take a minimum of 6-8 months (it cost us extra to break our lease at the old place).

All kinds of valid reasons have already been presented.

I have two examples.

First is the new house we had built by a new builder. Good kid, knew how, just could not get the subs he knew were the best because they were gobbled up by a larger company. Took 10 months to build our house. But, it was done well. Next door, that larger company built a comparable house in 30 days. In the 8 years we lived in our house, that house was sold four times, septic system overflowed twice, and it had to have a new roof in 4 years.

Same subs, different location on lot, cheaper materials, and no continuity between subs.

Second example. Two Habitat for Humanity builds, next to each other. One done with conventional stick framing, the other with factory built panels(12' long and others 8' and 10' long) that used the exact same type stick framing, same T1-11 siding, and roof trusses from the same company. The panel built house had 50 volunteers and six factory reps. The stick built house had 10 volunteers and one crew supervisor(me). In 7&1/2 hours, we had one long back wall, both shorter end walls built, sheathed and installed. There were four interior stud walls also built and installed(bare studs).

In the same 7&1/2 hours, the other house had all the exterior sheathed walls installed, all the interior stud walls installed, all the roof trusses(save the last two, because the next to last was missing) installed and almost completely sheathed, all the windows and construction doors installed---meaning the house was almost dried in(assembled so rain did not get in).

When you looked at the final results of the days labor, there was no easily discernible difference in the way the walls looked, but the process and techniques were way different.

Our builder is quite picky about the subs he uses (and why we chose him). He told us that there would be periods of no activity while waiting on his select subs. I'll take that over using whichever sub, good or bad, is available.

Across from us is a tract home development. I was talking with some guys on one of the framing crews one day and they said that when their crew gets a new plan it can take them two weeks to frame. The second time a week. Third time 3 days. Now their average is 2.5 days for 4 plans and 3 days for a couple of others.