I never thought, and do not believe that the manufactures ever meant that 90% complete was a statement related to time. Time to build a plane is totally relative to the builder. Similar to the way running a race or reading a book is. The 90% is related to the quantitative measurement of how many assemblies of the entire aircraft are complete, compared to the number of assemblies that require completion. For example a 90 percent complete plane should have 18 out of 20 steps complete, seeing how time is a relative matter, the final 2 steps could take any amount of time depending on the builder. One of the main advantages of the ARF plane is the workshop required to build and ARF plane verses a kit, a kit requires a table that must sit still throughout the completion of the main assembles, not to mention messy sanding, and a dirty work area. However an arf could be built anywhere and you can stop building at anytime and store the unfinished ARF anywhere out of the way.