When Warbirds came up with the ".dfuse" command a lot of things changed. Attack fighters could set the fuses before takeoff for 5,10,15, or 20 second delays. They would then make a low, very high speed pass and drop. (That's a whole new skill set) Then "x" number secomnds later, ""BOOM!"
I hate to use this word again due to being pounced upon by some folks, but delayed fuses were "real" in WW-II. I remember one "History Channel" presentation that duplicated a B-24 run where delayed fuse bombs were dropped at very low level. Some of them were set for as much as 24 hours! BIG surprise!
I first noticed the .dfuse addition when following a 190D at low level. I was about 1,000 yards in trail at tree top height and saw a puff of dust below the 190. I figured he has just jetesoned his bomb load, but seconds later my fighter blew up!(?) After that, any dust puffs under a fighter at low level meant an immediate pullup.
It's real, it's was fun, and in fact, it's was real fun.