The reader who posted this question is doing work that far too many people do: wrestling a real-world data problem into submission with brute-force columns. Their current solution, a cascade of helper columns that multiplies with every new subset of time, is a monument to patience, not efficiency. Our opinion is plain: this approach is unsustainable, and the real opportunity here is to step back and let the tool do the heavy lifting.
What this reader describes is a classic pattern recognition task disguised as a spreadsheet problem. They have time-series data, a threshold, and a need to identify the longest consecutive period above that threshold. Their current method works, but it consumes workbook real estate and mental energy. For 20 columns, each requiring their own helper columns, the workbook becomes a maze of formulas that is difficult to audit and harder to maintain. The frustration they feel is not a personal limitation, it is a sign that the traditional spreadsheet paradigm has reached its limits for this kind of analysis.
The better path is to think in terms of a single, dynamic formula that can handle the entire dataset without proliferating columns. In Excel 365, functions like SCAN and LET can replicate the logic of the running counter and the max extraction in a single cell. Alternatively, Power Query offers a more visual approach: group rows by a running condition, calculate durations, and output only the result. The key insight is that the data is already structured, six-hour intervals, consistent timestamps, a clear threshold. The solution should match that structure, not fight it with intermediate columns that duplicate the data.
For this reader, the practical takeaway is this: stop adding columns. Build a single formula that outputs the longest streak for the entire year, then reference that formula for each subset using FILTER or a date range parameter. The workbook will shrink, the logic will be transparent, and future changes will require editing one cell instead of twenty. The goal is not to find a clever trick, it is to design a system that works as hard as the person using it.