I think you are right about people submitting more puzzles. I also think there has been a substantial movement in the past year to recruit and train new constructors via a Facebook group that encourages mentoring and collaboration with new constructors.
In the case of LA Times, my observation is that approvals may come faster than rejections, which is because Rich often replies personally on ones he's approving (or requesting revisions), while his assistant sends the bad news (so there's another queue). But, yes, they are running around four months.
WSJ used to reply within a month, but now it's much longer. I don't send them much material so don't have a good feel for the time frame.
