Irena one of my kids is 2e (MG, dyslexic, CAPD, SPD, AS). She was struggling with the alphabet still in 2nd grade, as in she mostly had it but really didn't reliably have the name and sound for every letter. She was improving but limping along at the end of 2nd. Slow improvement through 3rd. RADICAL improvement through 4th. 2-4yrs advanced in reading by 5th....
For her I think that multiple things were at play, most of them 2E related - remediation of various struggles helped A LOT (OT, piano and swimming for left/right integration and crossing the midline, diet was huge, maturity helped) and she actually IS gifted, once she climbed over those massive obstacles her strengths could actually come in to play. She wasn't reading delayed because she was intellectually delayed and once the decoding and other technical aspects were finally under control she shot up to her actual intellectual ability really fast.