I have encountered this many times.

it depends on the hotel.

Some hotels add all the daily rates divide by nights and give an average rate.

Some hotels always charge a daily rate equivalent of the highest daily rate. (rip off)

top tip.

always check each day for rate fluctuations. if one exists call GP and get them to sort it out. every time i have called they have looked at each day and amended the overall daily rate.

knowing what your favourite or regular properties go for is a good indicator of one day having an excessive rate and applying it to every night.