Earlier quoted context omitted.
The science output of a given device usually shows heavily diminishing returns. I would say 12 Hubbles would have had at most twice the impact of 1 Hubble, probably less.
Definitely agree. However, the long tail will likely include discovering some more 'improbably' results. For example, the researchers who ultimately discovered Phosphine on Venus this week had early requests for observation time on telescopes denied and seemed to have to have been extremely persistent to finally get their chance.
That and the countless unexpected insights and connections between seemingly unrelated pieces of knowledge that can happen long after an initial discovery.