Courgettes always seem to do well on my plot. We've had the allotment for 3 years now (doesn't seem that long) and each year the courgettes have been prolific. This year they are as good as ever and we have had 3 pickings already.
When I arrive at the plot I always take a walk around to see how things are doing and what needs to be picked at the end of my days work. It almost seems as if some of the courgettes grow about 1" from when I arrive to when I leave. I always try to pick them when they are about 8" long as any longer than that and they begin to look like marrows and are then better for stuffing with mushrooms, peppers and stilton cheese.
I have 6 plants this year and find that this is just about the right number as the more you pick the courgettes the more they seem to grow. Unfortunately the season for courgettes is rather short, and as I love to eat them so much I must find ways of extending the growing season and then we can enjoy them for even longer.