Adobe made a simple interface change to transitions in the 26.0 update to Premiere that makes our editing life simpler.

Borrowing an idea first shown in Final Cut Pro, Premiere now provides handles on all video transitions. The handle is indicated by the small square (red arrow) in the top right corner, for the Out, or top left corner, for the In.

What this means in practice is that you can drag the handle, remember that’s the square (top red arrow), and see the results immediately in the timeline, as well as a numeric duration display indicating the amount of change and total transition duration.

Even nicer, you can simultaneously adjust multiple selected transitions across multiple clips located on one or more tracks.
NOTE: You can also add multiple transitions to multiple clips on one or more tracks by selecting the clips first, then applying the transition. (Default transition shortcut: Cmd + D)
This simple change makes modifying transition durations both faster and more accurate. Cool.
NOTE: Want to know how to select multiple transitions at once? Shift-click them.