We have a simple opinion on this: the COUNTIFS function is not the problem, the problem is how spreadsheet software evaluates time boundaries. The user who posted this is doing everything right. They have shift start times in a column, a window end time in a cell, and a 30-minute threshold stored separately. They have formatted their data as both time values and decimal equivalents. And yet, COUNTIFS keeps including the employee whose shift starts exactly 30 minutes before the window ends. That is not a bug. It is a logical trap that every spreadsheet user eventually steps into.
The trap is that "within 30 minutes of the end" sounds like a strict inequality, less than 30 minutes, not less than or equal to. But COUNTIFS treats the condition "start time is less than or equal to the end time minus 30 minutes" as an inclusive boundary. When the start time equals exactly 30 minutes before the window ends, the function counts it. The user's frustration is understandable: the logic is correct on paper, but the software interprets "within" as "up to and including." The fix is painfully simple: subtract a tiny increment from the threshold, such as one second, so that the exact 30-minute mark falls on the wrong side of the comparison. In practice, that means changing `R5 - V9` to `R5 - V9 - TIME(0,0,1)` or its decimal equivalent.
What this means for anyone building shift-counting workbooks is that precision in spreadsheet logic requires you to think like a machine, not like a person. The human mind naturally rounds the boundary to "at 30 minutes, you're out." The spreadsheet does not round anything unless you tell it to. This is not a failing of the tool, it is a reminder that every condition you write must account for edge cases. The user's deeper insight is correct: an employee who starts exactly 30 minutes before the window ends is too late to contribute meaningful work. The solution is to make the mathematical condition match that business rule exactly. Subtract one second, and the count becomes accurate. Add a helper column that flags employees as "include" or "exclude" based on that adjusted formula, and you eliminate the hair-pulling entirely.
The takeaway is practical: when you build a COUNTIFS formula that depends on time boundaries, test the boundary itself. Put a shift start at the exact threshold and see what happens. If the result does not match your business rule, adjust the comparison by a tiny amount. That is not workaround, it is how you make spreadsheets serve your logic instead of the other way around.