How do the problems work?

Hi all,

Since I started my journey in the chess world (October 27, 2021) studying seriously, I understand the importance of Puzzles. I do them every day and since I have a Gold account I do 25 problems a day.

However, I noticed progress in the Problems score is slow (on average 40 points a week).

However, I have a hard time figuring out how do they work.

I have 25 problems a day and for each of them I earn a score if I solve it, I lose a score in the opposite. So far so good. However, using logic I expect to have a higher score with most difficult problems, but this is not always true.

How does Chess.com calculate this score?

It's not clear to me what happens when I am not able to solve a problem. Will it be repeated me later in time?

Why sometimes I earn a score even if I am not able to solve it but only a part of it. Is time one of the parameters to calculate the score.

Now the most important question: what is your approach in solving problems?

I mean, you just try to solve them daily or you go back to failed one over and over again just to absorb new patterns?