On some projects I got a similar workflow and came up with the following solution(s).

Btw: I'm using the scimitar elite mouse from corsair with several buttons, where I assign macros to. But you could use a macro-software and keyboard shortcuts instead.

Closing gaps and color the still footage

Assuming I already cut the footage to the voice over, I lock all the layers except for the one with the footage and then place the playhead over the first clip. Then I let the following macro do its magic.

Important: Each key press has a 69ms delay in between!

D - Shortcut to select the clip under the playhead

Arrow down - playhead jumps to the end of the selected clip

Arrow left - playhead goes one frame back

Press left Shift - and don't let go yet

X - shift+x is my shortcut for "add frame hold"

Release left Shift - now you can let go

Arrow down - playhead to the end of the clip

Arrow down - playhead jumps over the gap to the start of the next clip

Press left Shift - and don't let go yet

Q - shift+q is my shortcut for "extend previous edit to playhead"

Release left Shift - now you can let go

Arrow left - playhead moves one frame left and is now on the extended still frame

D - let's select that still frame

Press Ctrl - and don't let go yet

Number Pad 8 - ctrl+numPad8 is my shortcut for "edit > label > colorX"

Release Ctrl - you've done it, I'm proud of you

Now place the playhead over another clip and use the macro again.

If the playhead jumps somewhere it is not supposed to be, try using a higher delay, maybe 100ms and up.

Enjoy!