A mid-western law department considered a consultant’s recommendation that it should tell law firms the levels of lawyer who should handle various activities in classes of matters. They deemed it a best practice to say that partner time should generally not be more than a certain percentage for given work, senior associate time not more than another percentage and so forth. For example, with contracts, partners are supposed to do certain steps (oversee junior counsel, give sophisticated strategic advice) and 15+ year lawyers do other steps, and 8-14 years out should do 25% of the work (as defined), and so forth.
The department working with consultant, made these determinations by type of work, complexity of work, tasks themselves, and experience levels of staff – really, cost.
I have my doubts that someone can so precisely define the roles of law firm lawyers in these buckets of tasks and percentages of time.