How much data do I need for a stable analysis? (Intraday)

First of all when working with intraday you must inherit from a daily chart. That will "stabilize" the cycles. Then follow the sequence shown in this playlist.

The recommended amount of data for each timeframe is:

• 1 min chart: about 3,000 bars (which is about 2 1/2 days of a 24 hour market, or about a week in a market that only trades 8 hours a day);
• 5 min chart: about 3,000 bars (about 2 weeks of a 24-hour market, or 6 weeks of an 8-hour market);
• 15 min chart: about 3,000 bars (about 6 weeks of a 24-hour market, or 4 months of an 8-hour market);
• 1 hour chart: about 3,000 bars (about 6 months of a 24-hour market, or 18 months of an 8-hour market);
• 4 hour chart: about 5,000 bars (about 3 years of a 24-hour market, or 3,000 bars for 4 years of an 8-hour market);
• Daily chart: as much as you like, although more is not always better. We recommend at least 8 years of data, 15-years is a good amount to work with on average.

More data doesn't make a better analysis. While, to a degree, this is the case in an EOD analysis, it isn't in intraday because of how inheritance works. When inheriting ST only really uses the most recent data, so there is no benefit in loading more data than the amount specified above.

Further points:

• Make sure that the setting Reduce data load to increase efficiency, under Tools> Options> Analysis tab, is checked;
• Make sure that the setting Allow automatic analysis period adjustment, under Tools> Options> Analysis tab, is checked;
• If you are loading data from a static source (such as ASCII, or NinjaTrader) it is a good idea to clean up your data files every now and then so that they don't get too big. Bear in mind that 1-minute data for a 24-hour market will increase by 7,000 bars a week. That could cause a serious overload on your computer's resources.
• For this reason we also recommend reducing the amount of historical data that MT4 stores if you are using MT4 as a data source.

For more information take a look round the Hurst Cycles Trading Academy. There is also more information to be found in the Online User Manual.