Other than the 3tph during very limited peak hour, it was always 2tph Victoria-Dartford via Bexleyheath, all stations from Denmark Hill. I used to commute from the latter, so know this route well. The last service used to be at about 1930, and then 2000, and finally about 2330 as others. It's very well used these days.
It is only ever 8 car due to the SLL stations' length (often 4 or 6 car forms though) so I'm not sure what the thinking is with Hayes, given the need to run everything at full length. Perhaps 2tph would be fast to Lewisham? But missing Peckham Rye and Denmark Hill would be unlikely I'm sure, both are now too busy and important. Denmark Hill was even added to the hourly Dover, plus a bunch of other peak mid distance services from Maidstone, Rochester etc I think. I only took them inbound to Victoria, and evening peak didn't have the reciprocal calls.