ALL INDICATORS ARE NOT CREATED EQUALLY.
It isn't that indicators do not work, it is traders do not apply them correctly.
Indicators should be time frame independent because price is the same on all time frames. Switching time frames does not change the price of the instrument.
Finally, traders must select the proper indicator(s) for the instrument(s) they are trading OR... select the proper instrument(s) for the indicator(s) they are using. Don't trade like a baby with a hammer and see everything as a nail.
There is no "magic" number. So using MA28 or MA5, doesn't really matter.
My video explains. Enjoy!