I'm not sure why those stations are 1tp2h
It is a legacy of the stopping service having been scaled back in the 1980s. For a long time, essentially the equivalent of one unit was used to provide the off-peak stopping service east of Guildford.
It is a really difficult position to increase the services at Chilworth, Gomshall, Dorking West and Betchworth. They simply can't justify their own stopping service if taken out of the Gatwick trains.
I guess that when new trains with better acceleration come in every station will get at least 1tph, but I'm not sure if signalling changes would also be needed to achieve that and the coveted third train per hour.
The service is currently the best compromise available with seven units. 2tph at Wokingham, Blackwater, North Camp, Guildford, Dorking Deepdene, Reigate and Redhill, 1tph at Crowthorne, Sandhurst, Farnborough North, Ash and Shalford, 1tp2h at Chilworth, Gomshall, Dorking West and Betchworth. Even with better acceleration, is the priority more stops at the local stations or better journey times to Gatwick.
If it was desired to get 1tph at the four stations, I reckon that it would probably be desirable to have 3tph north of Guildford only, with then the local stops across the two trains that run through to Gatwick. However, that could well need nine units which is a considerable uplift in operational costs relative to now.