.... light work.
Many hands make light work.
Two heads ...
Two heads are better than one.
Too .... and not enough Indians.
Too many chiefs and not enough Indians.
..., do it yourself.
If you want a thing done well, do it yourself.
... spoil the broth /brɒθ/.
Too many cooks spoil the broth /brɒθ/.
... is a problem halved.
A problem shared is a problem halved.