Not seeing much reason to do a lot for the others, save for Guildford if you’ve got the units going up and down the Direct early and late for diversion retention.
While there wouldn't be much "cost" in returning passenger service to the Reading to Guildford sector of the route knowledge moves, there wouldn't be much benefit either, and I speak as one who used them on occasions.
Timings varied over the years, but northbound was around 6am, and southbound mid or late evening. On the occasions I used them, there were only ever a handful of passengers south of Reading, and it wasn't unknown to have a coach to myself.
For the majority of journeys, the North Downs line and if possible a well-timed connection at Reading is far more useful. For Birmingham and beyond, it's usually quicker to go via London anyway (at least, it was until the Avanti meltdown).