Your question seems somewhat rigged towards saying Static encounters are bad, given the kind of example you cite.
Static encounters of the sort you describe are what I would call a Triggered encounter. That type of encounter is not one that I am not entirely opposed to. However, the players are going to be given every opportunity to discover that doing so would be dangerous long before they trigger it.
Triggered encounters of that sort are most useful for fleshing out a campaign world. You can set it up, and have the players hear of it. Then you provide a reason to go ahead and poke around it, and leave the decision up to them. The only real drawback is if the players never trigger it.
Encounters that are level appropriate are good. But there are a few drawbacks. First, if you only throw fights at the players that they can win. The one time you decide to change it up can backfire. Sometimes you just need to achieve a plot point, or establish someone as a badass.
Now, I use the term Tailored Encounter to describe something different. A level appropriate encounter is just a CR 8 monster against an 8th level party. Outside of some rather specific considerations, the players ought to be able to handle it. A Tailored encounter is a CR 8 encounter against an 8th level party where the opponents are optimized to exploit the parties weaknesses and neutralize the parties strengths.
As an example, consider this party:
8th level Barbarian, high damage output, low AC, likes to run out ahead.
8th level Rogue Archer, uses improved Init and likes to set up flanks.
8th Wizard, classic evoker who tosses Fireballs and Magic Missile
8th level Cleric, Buffs up and wades into melee.
Now, consider an encounter that consists of a group of 3 HD Hobgoblin Warriors with Mounted Archery feats led by a 3rd or 4th Level Sorcerer. The Warriors perpetually move away and shoot. The Sorcerer starts firing away with Blindness spells on the Wizard and Rogue, and drops a Grease spell on the Cleric. If the Sorcerer is hit with Silence, they all retreat and return when the Silence expires.
That encounter is designed to essentially kill the players. Using ranged combat with low HD combatants will neutralize the staggering melee output of the Barbarian. The Rogue and the Wizard have crappy Fort saves, and depend on line of sight to be effective. If they are hit with Blindness, their ability to perform in combat is greatly impaired. Using mounted archery also impedes the Wizards ability to hit the opponents with a blasting spell. The Cleric has a low Reflex save, and is vulnerable to Grease. And even if he does hit the Sorcerer with a Silence spell, the encounter description has them retreating until the Silence spell expires.
From time to time, I will tailor an encounter to exploit the players weaknesses, but I only do so if opponents manage to escape and report back on the tactics that the players use.
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