From highest to lowest probability of failure.

1. TA beginners.
Use lots of TA indicators, don't really know what they mean and whether they generate some real signal over noise.

2. Advanced technical analysts.
Experience gave them knowledge on how to deal with discrepancies of technical analysis, they may use less of TA indicators or not use them at all, relying on support &resistance or something like that.

3. Quantitative beginners.
They realize technical analysis isn't correlated to how prices move at all. May still fail due to many pitfalls of algorithm backtesting, like they may present some kind of Monte Carlo analysis as "proof"m when their initial assumption undergone too many "improvements" and as a consequence may be just data mined.

4. Advanced quantitative.
They understand statistics and probability well. They do backtests of their ideas only once with well defined and clear process.
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