Lol, ya all my groups have ben 3-4 players, 3 with any consistency and engaging in 1 maybe to 2 encounters per COMBAT DAY per session. I specify combat days because many session "days" are down time, travel, preparation, and just opening up story elements. That said, session days can fast forward a bit. We may only have 1 or 2 COMBAT days in a 4 hour session, but generally at least 1, thought we have had a few sessions without them.
Unless your actually in a dungeon, combat is a big moment that takes up a large part of a session between story, so my GM limits them. It also makes the Warlocks spell recovery pretty useless since the group would rarely ever have a more than one battle a day. In a dungeon however, I could see a Warlock suddenly becoming the anchor of the team and really powerful.
Even with a small group I could never do 12-16 encounters within 4 hours Real-time.
Does your group do hack and slay style only? Do you use the average for mob damage?
Do your encounters look like: You see a group of goblins they do not see you yet, party mage: I cast fireball DM: they all die?
I am clueless.