Any tips for late game?

I‘m ~1630 on HD and I believe my game is relatively decent until mid to late castle age, but when it comes to imp or even post imp I just get overwhelmed with all the things going on at the same time. So much that often when I’m able to pressure an opponent all game and my score is way higher I still lose in the end because I lose focus on certain groups of units or am not able to fight the opponent in all the places he has wants to fight me. Does anyone have tips to get better in this/ to keep a better overview of what’s going on and what I need to focus on? Thanks!