A free, no-software technique (credited within Sophie Society to "Zoki") for finding day-parting opportunities using only Amazon's own data and a spreadsheet.
The end result is an hour-by-hour picture of ad performance — e.g. a block of hours (such as 4:00 a.m. to noon) that performs well "from every perspective" — that can be turned directly into bid or budget rules for Day Parting (Amazon PPC).
Apply Format > Conditional formatting > Color scale to each metric column in the hourly pivot table, one rule per column since the "good" direction differs by metric: for ACOS and CPC (lower is better) set the scale to green at the minimum and red at the maximum; for CTR and CVR (higher is better) reverse it, red at the minimum and green at the maximum. Collapse the pivot rows down to the 24 hour-of-day buckets so all hours are visible on screen at once — the colored gradient turns a table of numbers into a visual pattern of green (strong) and red (weak) hours that's much faster to scan than reading raw ACOS/CTR/CVR/CPC figures column by column. See PPC Efficiency Metric Formulas (ACOS, CTR, CVR, CPC) for the underlying metrics being color-coded.