It is of course easy to overdo it and excess will go unnoticed but it's equally easy to use some experience and know that 3 or 4 pumps is all it needs.
Quite right Steve.
I am a 'jack it up and get underneath' type, but I find it very easy to avoid over greasing, I do mine every 1200 miles or so and find that 6 pumps from my gun is fine.
To be honest, I don't know what people are doing to put so much of the stuff in that it gets on the discs, you would need to put half a gun full in to do that.