When editing in Effect Controls Panel, show clip in Program Monitor... ALWAYS!
When editing keyframes in the Effect Controls Panel, the Program Monitor should show the current frame being manipulated, whether that frame is visible in the Timeline or not... PERIOD!
Only when the focus is changed back to the Timeline should the Program Monitor show the frame under the Timeline playhead.
Not being able to see changes being made in the ECP whenever a frame or keyframe is outside the clip's visible bounds in the Timeline is of ZERO benefit to editors, and worse, it results in a lot of lost productivity and frustration.
Editors often need to place keyframes outside the bounds of a clip's visible bounds, in order to create 'handles' for example, so that a scale and/or position animation doesn't suddenly stop halfway through a transition. This is basic editing 101. And yet the ECP is woefully limited in enabling even the most basic of editing tasks.
Please give this critical tool priority before creating fancy new tools that fewer people need.
Note: If the ECP frame is located anywhere within a Timeline transition, users also need an easy way to disable the viewing of that transition's effect in the Program Monitor. For this please refer to this FR that already several years old yet still just as needed: https://adobe-video.uservoice.com/forums/911233-premiere-pro/suggestions/41382235-transition-visibility-toggle-in-effect-controls-pa
As always, thanks for listening!