Daily or Frequent Isometrics?

Training
1

Anyone have or regularly use isometrics as a training supplement?
Just a quick 30 seconds of not too strenuous isometric holds?
How many movements do you use?
Thinking about
upper chest, hands clasped at chin level
Lower chest, hands clasped at waist height
Back, shoulders laterally abducted slightly, internally rotated, forced extension against immovable object.
Shoulders, forcefully abduct against door frame
Biceps easy enough
Triceps easy enough
quad flex, hamstring flex, calf flex

Can isometrics even help?
Better mind muscle connection?

2

Stuff like this definitely matters less than mechanical tension so if that is maxed, then this could give extra 5%. But if basics arent maxed, whatever advanced ideas might do, won’t be noticable