Out of curiosity, how does everyone deal with policy? What do you do when you start drifting into Easier to knock them back into reality, and how do you comfort your monster when you end up working it Harder?

I start scolding them if the get below 85%. It worked well even though they were always frustrated. I praised them when they got above 95%. Even some really stubborn monsters trained at 100%. I found if you praise them they will try to keep around the percentage of what they did that day. Scolding may seem harsh but it works like a charm.

Doesn't the lifespan loss from stress accumulate?

At present, I scold below 80% when using gadgets and praise above 90%. But I try to avoid their getting stressed as much as possible. I think I've been resting them too soon, mind, and have been missing training opportunities.

I'm not sure. None of my monsters had to be retired earlier than the others.

I believe Harrabcat did some limited research on that using a set of ten Pixies from a prior experiment. They all retired at the same time barring one which retired two weeks earlier.

While there isn't much to base this on, at least it looks like a little bit of stress every now and then isn't lethal.

Yes, I do the same thing Salokin does except when training without gadgets, I scold below 90%. It works like a charm, and my monsters tend to get at least 80% even on level four training gadgets.

They haven't retired too early either, so I wouldn't say that a little amount of stress is detrimental to lifespans.