Can the ADX be effective on the M30 timeframe?

For detecting trending conditions, I've heard that the ADX is ineffective below H1. Is this true?

Playing around with EURUSD in M30, i see some success with a period of 20 and a threshold of 40. Is that to be expected, or is this a fluke?

Asking anyone with ADX experience: from your understanding of the relative 'noise' of M30 (compared to H1), are such settings (a higher period and a higher threshold) a logical approach to getting clearer signal, or is this more likely a random fluke?

Thanks in advance!

have you looked behind the indi to see what its doing?

https://school.stockcharts.com/doku....onal_index_adx

provide a good description, and their conclusion is enlightening:

Conclusion
The Directional Movement System indicator calculations are complex, interpretation is straightforward, and successful implementation takes practice. +DI and -DI crossovers are quite frequent and chartists need to filter these signals with complementary analysis. Setting an ADX requirement will reduce signals, but this uber-smoothed indicator tends to filter as many good signals as bad. In other words, chartists might consider moving ADX to the back burner and focusing on the Directional Movement Indicators (+DI and -DI) to generate signals. These crossover signals will be similar to those generated using momentum oscillators. Therefore, chartists need to look elsewhere for confirmation help. Volume-based indicators, basic trend analysis and chart patterns can help distinguish strong crossover signals from weak crossover signals. For example, chartists can focus on +DI buy signals when the bigger trend is up and -DI sell signals when the bigger trend is down.

Ah, noted.
Thanks for this gem!