Is there any adjective synonymous to "to the point"?

Surely apposite is the word you want? And succinct means expressed both briefly and precisely, doesn't it? Etymologically, tightly delimited, as with a belt (It's a cinch).

Relevant and pertinent are synonyms to that concept:

Jack's and Jill's answers are quite relevant, but Mary's answer is the most apt.

Germane, apt, suitable, and apropos are some more.

If you desire still more synonyms, you could try thesaurus.com.

What about "succinct"?

This doesn't seem to fit with your second example, but it's what comes to mind when I think "to the point." Someone who digresses and takes their time answering is not to the point; they are not very succinct.

More in line with your examples, (but less, in my opinion, with "to the point") would be "accurate".

It's hard to tell what you're looking for, because "to the point" doesn't seem like the appropriate phrase to describe the scenario in the example. "On target" is something I've heard in a teaching context like that.