Saw that as well, good thing I bought on sale so it was only 1GBP per litre extra that I paid for the 1L bottles. 5L is probably perfect for long term 
Hmm, so I ride around 4-5 hours per wax application. And then around 15-20 hours before I deep clean the bike, and with that, I spray the chain with UFO, let sit, brush it, then rinse, then spray again, brush, rinse etc.
And thats maybe every second week?
I only remove the chain to clean when I change chain…
But thats for our road bikes, then we have 2 gravel bikes which runs wax also, and that we commute with.
So keeping 4 bikes in good conditioning have us run through some UFO Clean 
But the chains and other stuff lasts FOREVER with a good waxing and cleaning properly every 2 weeks.
We also exclusively run the new Effetto Mariposa FlowerPower wax now, super happy with it, both performance and ease of application.