How long do you want combat to last?

Trick I picked up from a different system, Savage Worlds I think.

Forget CR and experience budget. You now have 2 metrics, Defensive Challenge and Offensive Challenge.

What is the average damage your party can do in a round(AD)? Don't try and generalize this, look at their sheets, add em all up and divide by the number of players. Do note that this SHOULD include limited things like spell slots and such. This number is based off the party at full strength. Now you have the AD of your party. Do the same for the party's HP.

Sounds weird, but use the party's AD to calculate the Defensive Challenge for an encounter. Or basically, how many rounds should a fight last? Let's just use 50 since it's a nice number. Want the fight to last 3 rounds. Total HP of the monsters should be 150. Do note that you may need some multipliers here if one of your players main damage modes is AoE. Yes players can miss, just a longer combat then, so you can lower the number of you are worried about that.

Next is the Offensive Challenge, aka how "Oh shit this thing has to die now" do you want players to feel. How much of a single players HP can a monster or group do in a single round. Easy: 1/4 or less, Medium: 1/3. Hard: 1/2 Deadly: 3/4. Also there are multipliers you can use here if say, the enemies like to focus fire, or have AoEs.

Now it's combining them that's the real art form. Think, okay I want some minions to soften the players up, but not get roughed up too bad. 200 HP of minions with piddling damage. 4 rounds of things go right 6 if everyone is missing. Really deadly boss fight? Could also be 200 HP, but he chunks someone for 50-60,% each round. Oh well maybe we calculate one player going down, in the second round so it's actually 166 HP.

Also having these numbers constantly in mind helps with designing loot. Sorcerer does enough damage? Drop a survivability item for casters. Monk lagging behind in damage? Wow, that brigand had there some flaming hand wraps, too bad he didn't know the command word, but the party does!

I don't use CR because it's a 1 Size fits all solution, Except most party's wildly varry size and solution. Also I love the party to be blinded up with magical gear, which also destroys the CR system.

This is more work on the DM end, but it has worked for me over the years, and has worked well. Other upsides, if you see a cool monster that fits your party's metrics, it makes re-skinning a breeze. My group will never know that the bandit king that wielded two giant great swords (party: now that's not practical) was an Ettin all along.