In that field, the litigators have about 5x the prospect of making partner than the patent prosecution attorneys (litigators can leverage without necessarily having a book of business). And, at my particular firm, litigators who had clerked (particularly the at Federal Circuit) had about a 5x chance of making partner than litigators who hadn't.

By way of example, my BigLaw patent firm typically hired about 30 new attorneys per year and maybe made 6-8 attorneys partner per year. Typically 1 new partner was a prosecution attorney and 1 was a litigator who had not clerked. The other 4-6 new partners were litigators who had clerked.

Now this only illustrates how clerking opens doors in one particular line of work. But I'm sure there are lots of other examples in other areas.