Most indicators are transformations of the same four numbers. Adding rsi, stochastic-oscillator and williams-percent-r gives three views of one calculation, not three independent opinions, so their agreement means much less than it appears.
The real cost is decision quality. With enough tools on screen, something always supports whatever you already want to do, which turns analysis into a search for permission. A cluttered chart also hides simple structural facts such as where the last swing-low sits.
A reasonable discipline is to require each tool to answer a question nothing else on the chart answers, and to be able to state what reading would stop you taking a trade. If no reading would, the tool is decoration.
Related: confluence, oscillator, technical-analysis, confirmation-bias, price-action