I need to learn what?

Although it might provide a "nice diversion" to come up with a list of characters where radical (those that can be independent characters, at any rate) and phonetic have the same pronunciation, characters with radicals that are regularly simplified when in a consistent position (e.g. left-side 訁> 讠) wouldn't seem necessary to investigate (though I can see how 誕/诞 provided an "inspirational springboard" generally LOL), as there obviously isn't much ambiguity as to what is the radical versus phonetic within them.