The best timeframe for the bearish harami is the daily or weekly chart, where the pattern carries the most weight. The bearish harami pattern is most reliable on the Daily and Weekly timeframes. On shorter timeframes like a 5-minute chart, these "inside days" can often be noise caused by a temporary lack of liquidity. On a Daily chart, however, a Harami represents a significant psychological shift among institutional investors that often precedes a multi-week correction.
These are the standard timeframes used by most institutional and retail traders and investors.
Below the 4-hour chart, false signals dominate unless backed by volume and structure.