Ferrite heads aren’t relapped because its not worth it. Relapping a head only works out if you have a more expensive part and nearly all ferrite cassette heads are inexpensive.
For that reason I have an admitted bias against ferrite heads, because their tendency to shatter which happens to no other head type. Once that happens they are junk. Plus an extra 10dB of noise. I stick with metal heads for my recordings and archiving machines. So while it is true ferrite heads did last significantly longer when they were used, once they get enough usage the glass will crack and more times then not you are forced to replace the head. This is the kind of wear I’ve seen on many decks that used ferrite over the years. Doesn’t happen as much with cassettes because of the lower speed.
Trust me on this? They weren’t that awesome. The typical ’studio’ machines had the transport built into the mixer. They were considered semi-pro; the recording industry didn’t take VHS and Beta all that seriously even though they were a compact multichannel format. Their main downfall is they simply weren’t reliable for day in and day out 24/7 service, and when Something Bad happened the tape was often locked inside the transport; requiring a complete disassembly just to rescue a tape that might never play again. Thank goodness those days are past!!
You’re right it is a love hate relationship. The proof is in the pudding on the reliability of VHS. Good luck getting service on your VCR today. Good luck even attempting any repairs yourself. It is true they never manufactured a deck that was both high quality and reliable. Too bad they couldn’t make them as hardy as good old cassettes.
Funny enough I just purchased a Sony SVO 5800 with an old Betacam 2800 I’m going to be using for this kind of project. I’m going to attempt syncing the output of the Sony with the Betacam as a TBC. I’m posting in other VHS forums and this is going off topic, but it’s become a huge obsession of mine to find out how far I can take the format. I even purchased an ozone generator I use to clean my tapes. :)