“If you go flat out on the straight at Monza,” he says, “at around four or five hundred metres before the end of the straight, you have to downshift flat out because that’s faster.” At that point the battery has run out of its energy allocation for the lap and in the absence of the torque it provides you need the downshift to get the ICE’s revs to compensate. “I think that’s not the way forward,” says Max. “But of course, probably that’s one of the worst tracks.”
https://www.motorsportmagazine.com/arti ... e-a-point/
I think there may be a little confusion over the issue.
There is no limit to the amount of energy that can be deployed in a lap.
There is, however, an energy recovery limit (9MJ/lap) and a battery storage limit (4MJ).
The issue, therefore, is that the battery runs out of energy before the end of the straight.
If you run the MGUK at full power then you will run out of energy in a bit over 11s, assuming you had 4MJ stored.
Not sure how much time is spent on Monza's main straight, but it is longer than 11s. So they will have to run lower power from the MGUK.
The worst example, IMO, are Baku and Spa, where they have approximately 23-25s at full throttle.
25s is about the amount of time that 350kW can be deployed for the whole lap, assuming the allowed 9MJ can be recovered.