I think Paddock Wood to Maidstone West merits two trains an hour but I'm not sure Ashford merits four trains an hour?
Ashford could certainly do with a semi-fast in addition to the two stoppers via Tonbridge. Whether an extra two I wouldn't know.
Perhaps the second one would be better picking up via Maidstone East ?
Out of interest, how are they fitting these extra trains in ? I was under the impression that capacity on the two track Sevenoaks-Orpington section had been used up by additional Tunbridge Wells services a few years back.