1. I haven't really seen this effect, I very rarely get DCed at all, maybe it's my sneaky nature. It's probably not a bad idea though, to consider AI 3 as "normal" for Fleet DDs. A few 4s here and there. I'd not use less than 2 for any warship normally, at least not one at sea... training in the Inland Sea or Sea of Japan, maybe
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2. By this you mean the contact reports that are part of the "Group Properties," correct? I agree they need a massive lowering, I have already done so in my experiments. 20% might be too high if you change nothing else about the layers since the chance of a mission spawning for many of those is 70% every 140 hours. I dropped the contact report %, the % for many to spawn in the fisrt place, and I increased the time between attempts to respawn the convoy/TF/etc. In the case of TFs, I looked at the RT time to the point the mission starts, added a week or two, and used that.