That’s an approach. The MA’s are slow so only going to produce infrequent MA/MA crossover signals: also many of these signals will have missed a good early part of the trend and may actually be generated near the trend’s failure. But they can be powerful - have a look at AUD/USD, which gave a 20/50EMA crossover in early March - its still going.
Another approach is to watch the slope of the 50. When it changes direction, this can be useful. This usually occurs earlier than the 20 crosses it. See the AUD/USD where the 50EMA peaked first in early February and again later that month.
Another is to note the downward slope of the 50 and then see when price crosses down through the 20 or tests and is rejected by the 20, which happened numerous times almost every month since February. This offers multiple places to re-enter or add to a position.
Of course, reversal traders will say but the MA is too slow because price formed a high in late January. This is true, but reversal traders shouldn’t be looking at MA’s, they’re nothing to do with their game. If you’ve decided to be a trend-follower, then you’ve already decided not to trade until the trend is confirmed, so you take a lower risk for accepting potentially lower returns per signal. But you can always increase returns by pyramiding, and within a confirmed trend is the only place to do that.