How long should a successful rebuild take?

I'm going to float the idea that Payton's second rebuild would have taken (at least) a year longer, if that 2017 draft had merely been "good" instead of legendary.

The Saints very much looked the part of those 2014 - 2016 teams in their first 2 games of 2017. But once those rookies started settling in, and Kamara got to fully show what he could do......there's a reason people were starting to wonder if the Saints were possibly a SB team right then.