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