EASIER METHOD: this is a strat that I used for my 1:02 and 1:03 In Bounds runs. To do this strat, you don't pause in Platforms or After Big and fly above platforms. I recommend this to new runners, because you'll have more time to place down the boxes and if you fall in Platforms, you'll still have enough time to do the wallclip.

COMPARISON: There's totally a way to do the way through the door faster. For example: you could throw the box on one of the buttons in Three immediately and that could save like 2 seconds, but doing the wallclip is easier and unless you mess it up, it's faster.