Why?

Because, *if* they are grown alone you'll get a better crop from each
plant.

My courgettes were very successful last year.
I put each one on a heap of chicken manure and could hardly keep up with
picking them before they grew into marrows.

It's worse, I have ten now, growing away well.

Of course that includes IF you can separate them without major damage.

Starting point seed - single courgettes are fine.

Starting point is three well grown but seriously entangled plants - you
risk losing them all if you damage the roots beyond their ability to
support the extensive top growth.

So the real question is how much risk is there in separating established
plants.

Cheers

Dave R

I fail to see the point in growing loads of Large courgettes, I remember
when courgettes were picked and sold with the flower still on them, now
the things are often sold more like small marrows.
I'd rather grow 2 or 3 plants together if it will result in smaller fruit.
If you are growing for showing then it's a different thing.
David @what has been a sunny day on this side of Swansea Bay