Are window blind mechanisms worth repairing?

As far as the pulleys and internal mechanisms of a window blind goes, how would I tell if a window blind is worth repairing?

From looking at videos on the web, repairing the internal works of a window blind is often as simple as untangling a cord that is mis-wrapped on a pulley or putting rosin on a cord to keep it from slipping. However, in those cases, it seems to me that the basic design of the mechanism may be defective - or, at least, not robust.

Perhaps an expert on window blind mechanisms has knowledge like "Oh that's a ...such-and-such.. type of pulley. Those never work well".

Eventually the cords on window blinds and drapery rods get so dirty that they need replacing, but that must be a specialized skill. I've never met anyone who can do it.

had a blind replaced under warranty last month. the ring broke that holds the rod to open and close the louvers. We were told it was easier to replace the whole blind than to replace a small part.

Yes easy to fix normally, however, some blinds are so cheap, it really is not worth messing with them. I go to target and buy the cheap $3.99 blinds for our rental house. Replace them after every couple years. easier than cleaning/fixing them. OTH some folks have a month's salary tied up in blinds. Fancy things with custom colors to match the upolstery etc.