To get the best out of any analysis confluence between multiple tools is best because it gives a clear picture of where to possibly set take profit and set a stop loss in case of reversals. For me i Iove support and resistance and so I combine trend lines, moving average, time frame and indicative candle stick making sure my chart is as neat as possible and any signal outside this i avoid it. This keeps my trading discipline in check.
What are your own it can be beneficial to someone else.
Using 3 is enough, for me.
Too many trading indicators means a lot of lines in your screen, I guess it's fine if you're using PC but if you're on your smartphone, then I guess it's a no because for sure you'll be confused on what you're looking. A neat looking chart is the best to spot what you're looking for before entering and closing your trade, using many indicators are cool but I'm not really sure if you need multiple to make profits.