I'm not so sure about what my brain considers "combat readiness drills".

I've had nightmares where I was woefully unprepared for an exam that I went to school, running late, without any pants nor underwear on. And as I sat for the exam, I felt so nervous I wanted to pee. And so I did, right in my seat. Thankfully, I was able to wake up before I peed in my bed.

And then I've had a recurring nightmare where I was exploring an endless staircase, with a team of like-minded people. We kept going down and down, as some of our teammates eventually succumbed to fatigue, and then thirst as our supplies dwindled. In some versions, we ended up in the same place we began. In another version, we ended up at some large underground facility, totally dark except for the staircase where we came from.

The only nightmare I could ever consider "combat readiness drill" is a nightmare where I found myself to be a civilian caught in a crossfire inside an abandoned factory, much like what you'd see in action films. How I ended up there, I have no idea, but I eventually got shot as I was trying to escape, and died.