As a DM I have two groups. None of the players are extreme min-maxers, but their characters are all reasonably optimized: They have an 18 in their main stat at level 5, they took a race that gives a bonus to their main stat, they selected spells and weapons that do good damage, they try to have a reasonable armor class. Result: When I play encounters from published WotC adventures, the fights are often extremely short, and the monsters go down very fast. Generally the players have higher attack bonuses and armor class than their opponents in a supposedly "hard" encounter. At level 5 the players have to hit bonuses of between +7 and +9, but the monsters they meet often have armor classes of 15 or less, so hits are far more common than misses. In the other direction the monsters frequently need to roll higher than 10 to hit the group tank. And the players also deal more damage than most monsters they encounter. As I don't fudge dice, monsters can easily die before actually landing a hit. As the players know to concentrate fire on spellcasters, those usually go down having cast just a spell or two from their arsenal.
So I was wondering what hit points you choose for monsters. For example an CR 5 Barlgura demon with 68 (8d10 + 24) hit points. Do you use 68 hit points? Do you roll hit points, which on average should be the same? Or do you take maximum hit points, 8 x 10 + 24 = 104 in this case? Or do you just add more monsters to the encounters, compared to what is written in the adventures? My groups are 5 players, which might be on the large side and a big part of the problem, the encounters might be optimized for 4 or less characters.
