Problems can arise if your deployed forces are a lot higher than your maximum manpower when it comes to attrition. Also, lots of tropical sieges and what not can be pretty painful. Slacken standards is totally worth it imo. It drains professionalism rather slowly, and you can just spam out new generals to counter it.
One issue I'm running into is that I can typically siege the enemy forts with a single 30 unit stack. So I'll attach generals with high siege pips to my "siege stacks" and then send them out to siege all reasonably possible forts at once. But AI will form some 65 unit stack, stick a 2 star general on it and then start fucking up one siege after another for me when I'm not looking. Since I'm fighting multiple wars at once it's easy to miss something, so I started doubling up the 30 unit stacks into 60 unit stacks to avoid getting blindsided and been eating a lot of attrition from that.
Maybe I should switch up my template to 42-44 unit stacks, right now I'm doing 13-2-15 stack composition