The core rulebook table 12-1 : Encounter design gives the difficulty level of an encounter vs the APL.
In the the 3.5 Dungeon Masters Guide table 3-2, there was a repartition of the number of encounters (expressed in %) each difficulty should get.
Does anybody knows if the 3.5 table applies to Pathfinder?
Also, Wolfgang Baur wrote a series of article for Wizards a couple of years ago (Link) where he recomended approximately 13 encounter before a party would level up. Does this number still applies for the medium progression?
Thanks!
The table doesn't strictly apply, though it probably should (there's a discussion thread around here somewhere about how using those encounter rates makes a difference).
In 3.0 and 3.5, the number of encounters of appropriate EL was 13.3333 (which I always though was an interesting number) after level 3 (1-3 used an accelerated rate due to the way the XP chart was constructed). PF fast progression is 13 encounters to level. Medium is 20 and slow is 30.