I bought a 4L bottle three years ago for use in my compressor gun. I use it after every wash all year round on both bikes. There's still two thirds left.Long wet winter this year and it’s summer next week and the weather is still shit!
It works out quite cost effective when you consider how little you use. And I’ll only do it once a year.
I rode through road works the other week and it covered my bike in crap. Im so over washing bikes and cars too. Rather lay by the pool.