i was at 300 seconds & 29 deaths i think when i stopped at lvl 5, but i only stopped because i needed to sleep...
i think most of my deaths were on lvl 3? and i managed to get through 4 deathless
also i jumped off the corner of a block with a spike in lvl 1 and died a few times trying to replicate that and see if i could skip a bit of the level like this: