It depends what the astrologer is doing. They should state that clearly on their horoscopes.
Used to be astrologers based forecasts/horoscopes on the sun sign, because that’s all most people knew. But now, with it being far easier for people to know their rising sign, many (most?) astrologers are writing for the rising sign, and using whole sign houses.
By using whole sign houses for a rising sign horoscope, the astrologer knows exactly which house any transiting planet is traveling through in your chart, without ever seeing your chart (because each house starts at 0 degrees of each sign). This doesn’t work with placidus or any other quadrant system house. So, when you listen to these horoscopes, look at your chart in whole sign, for what you are hearing to make sense.
When these astrologers say “choose for your rising, OR sun OR moon”, I don’t accept that. It’s not workable.
Bottom line, if you want accurate horoscopes for yourself, you need far more than just what sign a transiting planet is in. You need to know exactly which transiting planets are actually m making contact with your natal planets, and with what kind of aspect, and for how long. Any general horoscopes you are listening to or reading online are just generic. Rising sign with whole sign houses is considerably more useful than the old sun sign horoscopes though.