Cross compatibility is key
Understanding the nuances that differs across the environments is underrated
When my kid was on a mattress, she was hesitant to move around. Later on, with the comfort of the soft surface, she was rolling around without caring about her head getting hurt or gravity.
Everything got changed when we let her crawl on the hard surface in the living room. She was getting hurt quite frequently - sometimes stepping on a toy, or hard landing on her head while rolling on the floor, or simply butting on something at her head level.