I also think that limits like 5000+500 are an excessive amount.
In my opinion, the optimal limit is something like 3000+300 or 2000+400. On the one hand, it doesn't allow you to relax and properly encourages you to speed up your thinking, and at the same time, it adequately allows you to think through the situation and avoid making big mistakes.
First, it was 1800+300, then 3000+400, 4000+400, 4000+500, and now even more people want to play. Maybe the limit isn't needed, and we can just play on an unlimited mode?
So, the limit of 3600+360 on the Portal (and +420 in TE-Lite) is too high (more than 3000+300).