I'm sure on some tracks, such as Vineta K (note yeldar2097's video) and Ubermall, because of the way you land, you can easily gain a good half second+ with BSB.
Depending on how effective the BSB is, yes it is. Sub-18 seconds laps without BSB on Vineta K (example) is impossible (to my knowledge anyway).
I SL regularly. I always keep finding new lines and places to BR/use the turbo and put in a lot of effort, time and hard work (as you say) in getting these times, but the simple matter is i'll know if I was twice as good as I am now, I still wouldn't be able to beat (or in some cases even get close to) most of the BSB'd SL times. It's just a fact.





