This is partly what drove Fischer's insane hatred of the Soviets.
The Soviets would even make arranged draws between themselves to all save their energy vs. Fischer.
Elite Chess is like taking 5 finals in a day for weeks. Rest is EXTREMELY important because many games are decided by a momentary let down.
At the time, pre-computers, the Soviets had almost all the top chess players and they collectively worked on innovations to beat Fischer.
He was really battling a system as much as a person.
The Soviets were famous for taking games into adjustment and then having all the worlds top player analyze all night as the player rested and then show him the fruits in the morning.
Today, with computers, adjournment would be meaningless. Run the computer, memorize the lines and play it out like robots
The level of detail in the series is amazing. When there is some random game being analyzed is a real and important one from that era - even if it's on screen for just a few seconds.
Even how the moved the pieces is realistic. It's weird - you can spot an experienced chess player just on how they move. The film captured is so perfectly it is clear they rehearsed even that.