I want to argue with you on the integrator delays, but I'm obviously doing something wrong.
fuel is sprayed. o2 reads oxygen content. ECM responds by adding/subtracting fuel.

in this particular control system loop, you definitely need a decently sized delay, otherwise the change happens so quickly that you end up modulating.

the only side effect of being too long is that changes take longer to occur.

so what?

a few percent of fueling error never hurt anything.

The more logging I do in warm temps the more fuel it's taking out (BLMs dropping when ambient temps rise)
warmer air is less dense. humidity also plays a factor. warmer air requires less fuel. the IAT temperature compensation is imperfect. it's normal for trims to change during things like weather fluctuations.

don't get too OCD about keeping your trims perfect. let closed loop do SOME of the work. that's why it's there. otherwise just turn it off like i usually do

IMO........in reality, engines don't actually need or want a stoich mixture most of the time. i suggest you try driving while adding/subtracting a bunch 'o fuel so you get a feel for how much AFR actually affects an engine. staring at these blm numbers too long makes you lose sense of that. just because o2 sensors only read stoich doesn't mean your engine really cares how close you are to it, and a truly awesome tune definitely doesn't have to hover around stoich for most of its life.

I've already bumped the O2 swing voltages somewhat.
don't go too far. the o2 swing voltages should ideally be the actual switching @ stoich point of the sensors as seen by the ECM. the further you stray from that value the less stable things get.