This is grossly inaccurate based on actual practice. An entire class took well over two years to go from initial UA to publication. Subclasses have taken 18 months to show up in an official content.
While the comment may have overstatted it a bit, the fist of thst was correct in terms of comments from JEC sbout the tole of UA in the last 12 months.
The point of emphasis was that
if UA material has not seen publish in a year, its likely because they found a need to rework it - something(s) wasn't right. The line was along the lines of "it will likely look very different".
Part of that was about feats as well...
But basically, it boiled down to this - they do not pull down old UA content they found yo be unacceptable. It hanging around for over a year is not a good sign it's ok to use as is - the reverse.
For classes and sub-classes he also clarified that some of the balance process testing is
not done at all for UA release. One example was the whole multi-class analysis. Thst comes well down the line sfter.
Obvioudly other factors play into release dstes.
So, all in all it did seem to be the case getting made that the longer something sits without activity on UA the lower the odds get of it coming out as is.