I used 3 tubes on my JL F15 kit, I didn't use it sparingly either!! I'd rather it had too much than too little on there. I used 4 inch nozzles too. I did hear somewhere that the length of nozzle is pretty important. The shorter nozzles don't ensure correct mixing leaving a weak joint.
I wasn't happy about wasting the hysol in the nozzles either, but sometimes you just need them as they are great for getting it just where you want it! Where I could I would mix it in a tub and apply with a spatchelor. I saved all my 'nozzle' gluing and did as much as I could all at once to save on waste/ nozzles.
If your ordering from the UK there are cheaper places to get from than the model shops!

Hope this helps.


Chris