I didn't include 125.2 on my list because that frequency, along with 124.3, is used for departures; and the choice (for pilots) between those two is quite logical. 125.2 is for departures between 225° and 44°, while 124.3 is for departures to the rest of the compass, that is, between 45° and 224°.
The reason for my question was that I was confused about the assignments of approach frequencies. It looked to me as though there was an overlap between 124.3 which is for approaches "from the west" and 124.5 which is for approaches from 225° through 44° which includes the west.
I now realize that 124.3 is the frequency for approaches and departures "from the west." I assume that's the frequency used by smaller and slower planes that fly into and out of LAX, while the other SoCal frequencies are used by the big commercial jets. (Correct me, if I'm wrong about this.)
I asked because I'm a very low time student pilot, training out of the Long Beach Airport. I've talked with ATC, but only with Clearance, Ground and Tower, even when I've flown to other area airports. I haven't yet flown anywhere that required me to talk with SoCal, so I was curious about when and how pilots use the SoCal Approach and Departure frequencies.
I wasn't thinking about hosting the LAX feed. The LAX Tower is hosted right now, quite reliably. I don't think I live close enough to LAX to be able to pick up LAX Ground, Clearance, or SoCal, reliably.