Counting number of times the same entry has been entered in the previous 7 days.

Zack BarresseI think I followed what you have there and it is clever.  My question to you is why isn't the following Sunday calc just:

INT((B3-1)/7)*7+8+TIME(5,59,59)

that said aren't you missing that 0.0001% of the cases where it is > 5:59:59 but < 6:00:00 and instead you should just make the following sunday comparison < INT((B3-1)/7)*7+8+TIME(6,0,0)

@John74Racing  Assuming Zack's comparisons are correct (they appear right on the surface except my comments) I think you could also use =countifs(....) with Zack's 3 comparisons.  I think the result should be the same but my understanding is that sumproduct is an array formula that if used in high quantity could slow down the sheet.

BUT my real reason for replying is to ask you about that "auto timestamp" and how it works.  you say the timestamp is in column B but the values in the formula are looking to see if it is 'A10'.  I know row 10 is just the example row you picked but I don't get the column A nor do I get how it works exactly.  I get that it is a circular reference and assume the trick is partly in that it is entered as an array formula (ctrl+shift+enter) and maybe has something to do with the convoluted comparison between CELL("address") and ADDRESS(ROW(A10),COLUMN(A10).  But that said if A10 is blank then B10 is blank (OK good) but if A10<>"" then it falls into the next condition which is always false because B10<>A10 so it will always fall into the next condition which is always true because B10<>A10 which means it is assigned itself B10 but B10 is still "".  I tried your sheet and couldn't get that timestamp to work for me.  Just wondering what I'm missing