The reason I like Q, W and E for these commands is physical as much as technical. The keys sit together and represent three editing decisions I make constantly: remove the beginning, cut here, or remove the end.
That creates a very simple mental model.
Once the layout becomes instinctive, I can move through a sequence with J, K and L and use Q, W and E to reshape it without continually changing the position of my hand.
Important
Your installation of DaVinci Resolve may not have Q, W and E mapped this way. The workflow on this page uses my custom keyboard preset, which you can recreate using Resolve's Keyboard Customization controls.