that shouldn’t take too long, as you’re snapping together larger and larger pieces as you go, no? for instance, once you get the first column stitched together, you duplicate that entire column, move over and repeat (merge by distance is the speeder-upper here, helps if your original single square is a nice even number in both dimensions, so you can just type in how far to move it on whatever axis, rather than having to line up by eye). once you get a wall done, you’d be duplicating that 4x for all the walls, assuming a square room.
that all said, last time i did a padded wall ( I've Gone Mad - #8 by RightClaw ), i did much larger sections and used a cloth inflate on them to help make them more pad-like, so i didn’t start with as many squares as you did (nor did i do all the walls, just 2 and the floor, as that was all that was needed for the final scene)