Make the function, Transport > Select Left/Right a two-state deal: The first state will activate either left- or right-side selection and the second actually lets you select time left and right on that particular side. This makes the process of selecting time with keys a lot faster.
- Press Shift+Arrow (Left/Right) to initiate selection mode on either left or right side.
- In this state (while still holding down Shift), use Left and Right keys to adjust time selection on the side you chose to adjust.
- Release Shift to exit time selection mode.
Place cursor somewhere in the waveform.
Press Shift+Right to initiate right-side selection mode.
Adjust right-side selection with Left or Right arrow keys while still holding down Shift.
Release Shift to exit right-side selection mode.
Press Shift+Left to initiate left-side selection mode … Rinse and repeat.