I was interested to see that the original GI article (assuming I found the right one) doesn't place a wandering monster as such, but a 'reinforcement' monster in a place the players have already explored but isn't currently visible to them. It won't get to attack immediately and indeed it might be held back until more reinforcements have accumulated. That makes more sense of the high frequency, I think.
There is one other consideration to take into account (if you haven't already), which is how it
feels to the players.
For example, if the WM appears on a Hero's move, that's more efficient because the Evil Wizard player doesn't have to roll each turn. But on the other hand, the EWP doesn't
get to roll each turn. Rolling gives them something to do on a turn when otherwise they would be doing nothing. That could be especially important for HeroQuest's original intended audience (kids).
Also, it's already frustrating for a player to roll a double 1 and not be able to move where he/she wanted to. Having a WM pop up as well would be extra-frustrating. That may be a feature rather than a bug, of course.
In Milton Bradley's Space Crusade, when you shoot at an enemy, you only roll to 'attack'. The opponent doesn't get to defend like they would in HeroQuest. You just roll your dice and if the number is high enough you kill the enemy. In terms of time, this is quicker and more elegant than HQ. It effectively combines "do you hit it?" and "do you hurt it?" into a single roll. In SC every player controls multiple models, and there's more attacking going on than in HeroQuest (because everyone has guns and can attack anyone they can see, instead of having to be adjacent), so this stripped-down system was probably the right choice to keep the game moving along at a brisk pace.
However, the
feeling of shooting at enemies in Space Crusade has always bothered me, ever since I was a kid. Because the single roll makes no distinction between hitting and hurting the enemy, it tends to feel like most of your shots miss by a mile and that your troops have worse aim than Star Wars stormtroopers. Plus, when you're being shot at, you don't feel like you have any agency to dodge or shield yourself. You just helplessly watch your models get bumped off. In HeroQuest you get to roll defence dice, and in Warhammer you get a 'save' roll, which makes you feel like you're reacting to the enemy and participating in the game--even though it's less efficient. Again, this can be particularly important for kids.
Bareheaded Warrior wrote:The other aspect it whether you would accept or change the WM in various published quests, as some quests feature a powerful WM, such as a CW, which I think could be game-breaking, especially in combination with some of the higher frequency options above.
Yes, that's the trouble with house rules--they tend to lead to other house rules, because they disturb the overall balance and assumptions of the game. It's like putting bigger wheels on your car for one reason or another. It seems fine until you realise your elderly mum can't get in because the door is higher off the ground, and the centre of gravity is higher up so you're more likely to roll over in a crash. Suddenly you need to bolt on an extra step and a roll cage.
For my part, I'm now leaning toward a 1/36 chance, so a double 1 (or two black shields) on two dice, rolling on the Evil Wizard player's turn instead of moving and fighting with monsters. (That way the roll can be made either when there are no monsters, or when the EWP is trying to lure the heroes through the door into a room with monsters.) I think a 1/36 chance lessens the problem of the especially powerful wandering monsters in certain quests, and doesn't put too much time pressure on the heroes' exploration.
I've played a lot of Warhammer Quest, which has a 1/6 chance of something horrible happening every turn--sometimes up to a dozen monsters appear at once. It's incredibly tense and a standout feature of the game. But it gives you no time to hang about or look around. Got to keep moving! Fine for WHQ because it's more about fights than exploring, but not ideal for HQ.