There are a lot of indicators so we can use the one which better suits to our needs however this is also good if we learn the price action instead of the indicators. Because price is the one which is actually happening in the market at the moment whereas the indicators show lagged data.
We have own choice here in trading, although trading without the indicator, usually relying on candlestick pattern, and price action, there are many patterns in price action trades, triangles, abcd pattern, Gartley pattern etc
Indicators are the most important tool for analysis, which should not be missed, because with their help you can implement and start up almost any trading system. So, they should be studied unequivocally. But as for their quantity - here the question is individual. As much as you need - as much and use it.