Hello Codeforces community!

I recently reached the Expert tier, but I've noticed my rating has been hovering around the 1600s for a while now. I'm struggling to make the jump to Candidate Master and would love some advice from those who have successfully crossed this bridge.

Currently, I usually solve A, B, and C in Div. 2 rounds, but I almost always get stuck on D.

A few specific questions I have:

Practice Strategy: Should I focus mostly on solving problems rated 1700-1900, or should I be learning new, advanced algorithms?

Math vs. Implementation: I sometimes struggle with constructive algorithms and heavy math. Are there any specific resources you recommend for these?

Upsolving: How much time do you usually spend upsolving a problem before looking at the editorial?

Any advice, practice group invitations, or resource links would be highly appreciated. Thanks in advance!