In his book "Thinking, Fast and Slow" Daniel Kahneman described well the dynamics of relationships based on praise and criticism. It often happens that bosses or parents praise and criticise their subordinates and children. They did their work well — the manager praised them, and the next time they do worse than the boss expected. The same with children: they passed an exam well — the parents praised them, and on the next exam the children do less well or run into greater difficulty.
The first wrong conclusion a boss or parent may draw is that praise always relaxes and criticism and punishment motivate. Some may stop giving positive feedback to subordinates, others may stop praising children, and that won't lead to anything good. The second, and main, wrong conclusion to draw here is that neither praise nor criticism, by and large, work in the long run at all. I'd even say: the result depends little on criticism and praise. Of course you can motivate or scare an employee or child, and then on the next exam or workday they'll deliver excellent results, but that can't apply to every single work or school day. The point is that bad and good results are nothing other than deviation from the mean. Deviation from the mean is a perfectly normal and everyday phenomenon. One attempt will sooner or later always turn out better than most others, and vice versa — sooner or later there will be one when the result is worse.
Kahneman illustrated this with the example of soldiers. When they were praised for a good current result, the next time they didn't deliver equally good results but did slightly or even noticeably worse. Those who did poorly were instead scolded and criticised, and then the next time they did better. The officers thought that praise and criticism worked: one relaxes, the other motivates, so they used criticism more often. Yet they didn't understand why their assumptions worked often but by no means always. In fact they had no idea that neither praise nor criticism really work here, and that this is a classic example of regression to the mean. Someone who did poorly will most likely do better next time relative to their current results, while those who did well — better than average — will next time, at best, show the same result, and at worst do worse than the rest.
Applying this to planning, remember that your successful days, weeks or even months are by no means always a good indicator of your capacity — how much you can get done. There can be many factors that made you do your tasks very well and quickly in a given week or month, or on the contrary very poorly and slowly. From the current stretch it may seem that the next stretch will be equally productive or unsuccessful. But it's always worth remembering regression to the mean. Don't draw conclusions from a small time sample alone; to assess your capacity choose a longer period so as to understand that very average of your capabilities and available time, from which in different days and weeks you'll manage more in some places and less in others.
