Which one is correct? the last or last

What is correct “the last” or “last”?

I haven’t read any book since “the last Saturday”/“last Saturday”.

I read an article that we use last before a specific past time reference such as Monday. So day in a week are never preceded by THE LAST but just by LAST apart from if it is a specific reference in time e.g. It was on TV the last Monday in November.?

Thank you

"last Saturday" means the previous Saturday, the one before we are talking.

"the last Saturday" means the final Saturday in a period of time.

So "The last Saturday in November" is perfectly correct. So is "I haven't read a book since last Saturday"; but also "I haven't read a book since the last Saturday of November".

"the last Saturday" without a qualification would mean the final Saturday of all time, for example if the Earth was being destroyed in less than a week.