No. I mean that (on any timeframe) just reaching the 80/20 level is NOT a reverse trade signal at all.
All that reaching that level indicates is that the trend is strong. And it can continue in the same direction for some time even after reaching these levels. At best, it is warning you against entering a new position in that same direction because there might be a reversal or correction soon. And the shorter the timeframe the less accurate such levels will become.
Here is a recent example from EURUSD 1H. The RSI reached the 20 level (ringed) and there was a correction thereafter, but the downtrend continued.
So there is a choice, depending on one’s trading style, You could try to trade the correction, maybe hoping it will turn into a full trend reversal, or you can use it as an opportunity to wait and get into the same downtrend at a better level. Or, if you are already in the trend, it may be a useful indication to take some profit off.
But either way, the RSI itself is not a reversal signal, rather it is just measuring the current “temperature” of the move - when it starts to boil then it is usually time to turn down the gas. This happens when the supply of new entrants to the trend slows down and the RSI moves off the extremes - but it does not automatically mean that those already in the trend are exiting - although it might! That is why something else needs to be used to trigger an actual trade entry.
Another similar way of using RSI (which I use as well) is to watch for the cross over the 50 line. In these cases (such as the HLHB method here on BP) other means are used to trigger an entry and a cross over the 50 line is a secondary confirmation of the possible start of a move and helps avoid some fake signals.