I used to do this too. For what its worth I used 1l Silkolene bottle per tank, Cost about £6 per bottle if you bought 5. Oilman might be an option for these with discount etc.
I never bothered "Running it through first" as I was using it for protection. If 99-Ron was available I might have used that but If my car was mapped to run 99 then I'd still probably throw in a bottle of booster.
My reasoning was if the car is running fine on the road without det, what will it be like after 20 minutes of being ragged around a track where under bonnet/engine/charge temps were all significantly raised.
IMO, even if octane booster does not add any more power, the engine always runs smoother.