No, the "settling in" thing doesn't make sense, either it's fixed or it isn't.
On this vintage 104 engine, I think maybe the best course of action may be to hang a fuel pressure gauge on it and try to get it to act up, that way at least you'll be pretty sure it isn't a fuel related problem. I can't remember on your car if it has a fuel pump relay or a slightly different type of relay called an MAS relay, I tend to think it's a MAS relay. If this is intermittently failing it could be causing the fuel pumps to stop working.
By the description you gave I would have sworn it had to be the OVP relay, maybe the MAS relay could be failing in a similar manner.
Another thing a tech could do is if it were in a failed state you could remove the MAS relay and install a jumper wire to see if the pumps then run and the car starts.