I think it varies by system and root cause. In my case, my SE/30 was exhibiting this issue and it eventually led me to replace a video mux chip if I recall, not to mention a complete recap and all of the cleanup that goes along with that. In the process of eliminating the problems, I had to remove the ASC sound chip, add bodge fixes on SCSI lines, and even had to run a bodge from front to back because of rotten/missing traces and vias. Along with troubleshooting the analog board, it took me a year to fix my SE/30. Was my simasimac symptom terminal? It might have been with less patience, but theoretically, if you can find and fix all of the contributing issues, it's not hopeless at all.
It could have been a lot worse too, like bombed battery issues or just too many chips to replace and broken traces to correct. I guess what I am saying is terminal for some people is just an added challenge for others.
I repaired a Classic in similar fashion exhibiting simasimac symptoms. Again, it was several bodge fixes over rotten traces and a recap (of course).
I have seen plenty of examples in my research to fix my own issues where a recap and cleanup was all that was required. YMMV, but I might take the plunge again someday if I come across a simasimac system that needs help.