I also don't believe this 1-2-3 rule fits the ferm process very well. Fermentation is both simple and complicated at once, and the complicated part is invisible to us brewers. The yeast are doing their thing, and the shift from one stage in their lifecycle to the next is gradual and overlapping, and each batch is entirely independent of every other batch. No two ferms are the same.
I would propose a 3-3 timeline might fit more batches. Allow three weeks for fermentation to fully finish and clean-up, and three weeks for bottle priming (less to keg). If you allow for three weeks fermentation, you can later decide whether to secondary (or not), or to keg after 17 days if you taste it and think it is fully ready.
Either way, you've allowed time for the yeast to do their job and you can likely eliminate diacetyl, acetylaldehyde, and any other flaws that arise (primarily) from rushing the initial ferm phase.
We've probably all had a batch in which the last bottle/pint we drank was the best in the lot....because we waited. The sample principle applies to the ferm, which affects every glass we drink. Give each ferm the time to be the best it can be.