perhaps because we holders and the general joe finds out after...

perhaps because we holders and the general joe finds out after the fact that PL5 was essentially a hybrid development lot specifically designed to provide mask and etch improvements from pl4 into pl6 - that would suggest not all went to plan with PL4 mask/etch - it also suggests that these 'variations' would impact pl6 manufacture - it also explains the 'live data feed' between pl5 to 6 aka test on 5 to manufacture 'process' on 6 and the required delay in manufacture

it seems now there were never going to be data test comparatives on performance between 4 and 5 as the purpose of 'hybrid' 5 was mask/etch variation adjustment into 6

this was material information imo
is it de risking in practice? - if it is successful when 6 pops out - until then best to treat it as 'discovery'

this is my opinion based on what is clearly hindsight
add the timeline in and make your own assessment -

glah