I'm sad that this post has been up for a couple days and there haven't been any replies. I wish there was more engagement on here aside from the memes. Thank you for taking the time to post it.
I was vaguely aware that this existed in the DMG, but I have never used it. I do like how it extrapolates the likelihood of hits based on the creature mechanics. In the rare cases I've ran mass combat, I just roll like single combat, but I apply the d20s for batches of baddies and apply average damage. I might divide the group into quarters and then roll 4 d20s for their collective attacks. There is also [Mike Shea's assume a quarter succeed guideline](https://slyflourish.com/one_quarter_succeed.html), which is a similar deal but with no rolling.
What I struggle with is what mechanics to use when the characters are overwhelmed. It's one thing to use streamlined mechanics for when the characters are wading through enemies, cutting them down. But, if they get themselves into a situation where they are overwhelmed and on the ropes, the mechanics used could be life or death. I would hate to use a streamlined mechanic in those situations and have it result in a character death or a party wipe. Would the outcome have been different if I had used rolls for each monster? Who knows. It's just something I would think about in those circumstances.
