Medial deltoids are my weak spot. I’ve tried every movement under the sun. I’m finishing a fat loss phase, so shoulder spec will be next, after an overall mass gaining program.
Try big compounds and isolation movements. Deltoids, like abs and pecs, have different portions which you can’t really isolate, however you can emphasize them. For example: DB press with neutral grip, then “pitcher” lat raises. For me, the neutral position in the press and the “pitcher” movement in the raises allow me to reach a better mind-muscle connection.
Try various rep schemes. Medial delts are slow-twitch dominant, but you don’t want to forget the stimulation of those fast-twitch fibers, with a better growth potential.
Don’t forget constant tension. While performing lat raises, it’s common to see 1-2 sec pauses between reps from guys who want to move more weight. Don’t. Imagine it as a big and continuous repetition. And, by the way, the cable version is not inferior. Constant tension is precisely its main advantage.
That’s what I can tell you from my little experience. Hope this helps.
