Why set hot cues at the beginning of phrases?

Almost every video I watch says to set hot cues at the beginning of a phrase or when the beat drops.

Why don't DJs set the cue point 16 or 32 beats before the phrases start so that they know when to mix in phrases?

As I'm learning, I find myself often missing the timing of phrases when I transition between songs.

Let's say track 1 is playing and the phrase is going to end in 32 beats. I want to mix in a phrase from track 2, and I go to my hot cue where the phrase starts. Then I jump back 32 beats so that they line up. How do I know ahead of time when track 1 is also 32 beats from the point I want to switch tracks?

Edit: For clarification-

I'm wondering if there's a good way to set points in my tracks so that I can do transitions that will line up at a certain point in both songs. For example: track 1's phrase ends while track 2's phrase begins. I'm finding it difficult to line up that point in both songs if my hot cue point is at the beginning of track 2's phrase.