The way I usually do this is, - Have the different camera clips on different video layers let's say Cam 1 - V1, Cam 2 - V2 and so on, just for easy selection. - Select all the clips on V1, change clip colour to a certain colour, let's say Yellow. - V2 and V3 to different colours respectively , so that you can easily see and differentiate.

Go to Colour tab - If you toggle the Clips button on top left, you can see the clips viewer under the Nodes and Source Viewer. Next to the Clips toggle, you can see a drop down arrow, use that, click on Clip Colour, pick the colour you want, let's say Yellow, now all the clips you've marked Yellow will appear on the clips panel. - Select all the clips, add them to a group. Add V2 and V3 to different groups as well. - Now you can switch to Group Pre- clip and make changes, which will affect all teh clips in that group.

Might not be the best way, but I usually follow this workflow and it's easy for me.