Justin,
The house you show is what I would consider a standard three bed.
Around my locale I would be charging around the £8.50 mark, but that would not include the frames, nor a conservatory if there was one.
I rarely do domestics now as my round is commercial, and using the normal method of cleaning using a squeegee I would expect to take about 20-25 minutes to clean a property of this size. Including turning up, setting up, getting paid & reloading ladders on car and so on.
Three in a row would of course be quicker and I am also not talking of working at top pace, just the sort of pace that you would be going along at if you average things out over a day or so.
Considering you also do the frames with your WFP, how long does it take you to clean this house?
For me a full frame clean, if done every month would add about 10 minutes or so as after the first time, and especially if they are UPVC windows a simple wipe over with a damp scrim before you wash with applicator would suffice.
regards,
Ian