I'm a bit of a perfectionist, and also get very little free time to build.

If i'm lucky i get about 2 hours one evening each week and perhaps the occasional saturday to build. I try to fly every 2nd Sunday but will sometimes elect to build instead of fly if i'm anxious to get a new model built.

Often i'm not happy with the supplied hardware so will waste time waiting for parts to arrive in the post or for spare time to visit the LHS.

At that rate the average ARF takes me a couple of months to complete.

The longest ones for me seem to be Great Planes models (Super Skybolt & Venus II) which had no problems, they just took a while.
The fastest was a Hangar 9 Tango which had practically everything pre-done (control horns, pushrods etc).
The best was a Sebart Electric model which was superbly well made and accurately constructed. I went together just as it was designed with no need to re-engineer it like i've had to do with others.