When wanting to apply transitions there should be a preview.

Workflow is key. A big obstruction at the moment is when wanting to assess transitions over a composition there is no way to select either a clip or a selection of clips and be able to preview entry, exit or cross. 

A simple toggle icon in the effects panel is all you need, when selecting the clips you desire to preview you could simply toggle an icon ‘In’ ‘Out’ ‘X’, then playback desired area and this will show the user how the transitions affect the composition. It also allows for quickly noting what transition works where.

Effect controls should also reflect this feature and be able to apply changes across selected clips.

Ideally a master preview selectable icon could allow for time durations to be selected based on the users needs.