Because this is a melody composed of four 16 partials in series. The basic theme melody of 55616 532 2312165 is like this. You can listen with your ears, emphasize the big finger sound of your right hand, and you can hear this melody.
If I remember correctly, it starts with the high octave and then repeats with the low octave. The high octave requires playing a little stronger, and the low octave is just an echo or sustain, which can be a little weaker. Only the first 6 and 15 15 are emphasized. They are pleasant sounds.
* * * There are two ways to play this paragraph:
First of all, all the big fingers of the right hand+three fingers of the left hand
Second, all the four sounds similar to 53 16 are completed with four fingers of one hand, and the left and right hands alternate, generally the right hand comes first. For sounds like 6363 15 15, use the method you mentioned above, and the right hand goes first.
I suggest you take one of the above methods to practice according to your own level and finger habits, which is fixed and not intermittent, otherwise it will be difficult to be proficient.