I ran about 15 vaults without being able to get all 3 chests, particularly because of the last room (melee q_q)
Switched from playing on mouse and keyboard to playing with a controller and wallah, I can take tiny steps and make minuscule movements while fighting that I could never do on mouse and keyboard. Been able to have several flawless runs since then.
This is for anyone who like me, was frustrated by not being able to navigate through all the traps while having enough to open the final chests.