If we analyze the role of the HR function in a partnership firm (here we are talking about large multinational partnership firms) some interesting dimensions emerge.
One of the key factors here is that a partner is an owner of the firm in addition to being a manager. Now, if I am an owner, I might feel that it is my privilege to run the firm (or the part of the firm that I am managing) 'my way'. It might also lead to a tendency to make 'sporadic interventions' in people related processes/ decisions. Thus some of the partners might view well defined HR processes as impediments to their 'freedom of operation'. This might pull the firm towards functioning like a 'family owned firm'.
However, most of the global partnership firms have well designed global HR processes. It is essential to have these processes to manage the scale of operations and to attract and retain good talent. Also one of the key attractions for working in a partnership is the opportunity to grow in the firm and become a partner/owner. Well designed HR processes are required to facilitate this and to give the employees the 'comfort feel' that this is possible .
So there are two opposing forces here, one pulling towards a highly 'personality driven' way of making people decisions and the other pulling towards a highly 'process driven' way of making people decisions. The HR function in a partnership firm experiences both these forces and it makes the role of the HR professionals quite tricky. Often only a 'dynamic balance' is possible and the equilibrium point keeps on shifting. Depending on the degree of credibility/respect that the HR professionals in the firm enjoys/develops (in the eyes of the partners) more positive outcomes becomes possible from this dynamic interplay of forces.