You could (all sold out now) buy kits that include all the parts and the 80percent receiver for Sig P320, Glocks, 1911s, AK, and AR15s.
To complete the frames the p320 is the fastest at about 10 minutes, the slowest is the 1911 taking about an hour.
Assembly of the actual gun, glock is the fastest at 10 minutes and the AK is the slowest at about an hour.
You must be one hell of a builder to assemble and AK in one hour...I guess if the barrel came populated, the kit was already demilled, and you did a screw build. But still an hour is pushing it and you'd have a very sloppy AK. That's just from my experience building dozens.
I know you were just using it as an example so not harm done. The argument they make that you can build a kit in minutes always makes me laugh. Those who build it in minutes will probably have it blow up in their face.