That 3:30PM out of Flatbush is almost NEVER an express run in the Bronx. By the time it gets to 3 Av, there are still LITE trains coming down the middle track, which deadhead to the Bowling Green loop and get used as gap trains for the PM rush. They don't start running the express trains until the last southbound train has cleared the middle track, so it's really more like the 3:55PM out of Flatbush.
Also note that those N/B trains that terminate at E180 at the end of the AM rush sometimes make an express run from 3 Av-E180 if there's a 2 right behind it. And those last Brooklyn S/Bs can terminate at either Utica or New Lots depending on where they want to lay it up and if they will make a connection to a 3 at Utica. Crews are instructed to sign up the trains as going to Utica unless/until we are told otherwise, even though the countdown clocks all announce New Lots, which often leads to disputes with the customers when we actually try to clean out the trains.
You didn't touch on the whole Nereid-bound 5 train issue. Those trains will fill in whatever White Plains Rd service is needed at the time. If it makes a connection with a 2 at E180, the 5 will most likely get sent up the middle to Gun Hill Rd and either terminate, or cross over to the local after Gun Hill and make the rest of the stops to 238. And if there's no 2 in sight, it will make all local stops to 241 and get sent back south as a 2 (241 finally caught on to Flatbush's tricks!)