The real interesting point is the multiplicity of a people's representation.
Is the limitation to only two wings (as in the USA) a good thing? Is a multi-party system, which basically requires koalitions, better?
Koalition governments tend to be less stable - but are more diverse in their representation of the public. One could argue that it is less efficient, however the obligation to compromise to find consensus gets decisions thought over more than once. A strong opposition is not inherently bad - safe maybe for the respective government...
Actually, in forms of governments the Romans in their prime were more flexible and wise:
Not a single man at the top, a senate as a sort of check and balance, and in times of crisis the possibility for a time limited dictatorship.
And the top power positions limited in time for only a short period.
The system began to fail when individuals started to cling to power... (A very natural trait basically - as a Roman once said, probably from living experience: "homo homine lupus est"!)