Pasta cooking time

A table like you're asking for can't actually exist: doneness depends on the internal temperature and hold time of the food, not the oven temperature; your table is missing some columns.

So, there are a couple variables you're not accounting for—the biggest one being the shape and size of the meat. A ½" thick steak will cook much quicker than a 1" thick steak. The other one is the starting temperature—a steak that has been left to warm for an hour before cooking will cook quicker than one straight from the fridge. You could, I suppose build a table for all variations of size (steaks go from maybe ¼ through 2"), initial temperature, and desired doneness, but that'd be a large chart, just for a steak (and it'd be different for a T-bone or porterhouse due to the bone).

More reasonably, you could just use a food thermometer. Then you only need to worry about the temperature for desired doneness.

The recommended cooking time is only a guideline. There are a variety of factors that influence cooking times in a substantive manner. For what it's worth, water in the water pan is not one of them.

The purpose of the water in the water pan is to act as a heat sink, in order to prevent temperature spikes. Anyone who claims that it helps keep what you are cooking moist should be summarily ignored. One of the more likely scenarios is that the thermometer is either inaccurate, or it is not an accurate reflection of the area in the smoker where the meat is being cooked. There are no guarantees that the temperature you read at one point is constant throughout the smoker. In fact, it is almost a certainty that the heat sink (water) will cause a cooler area in its immediate vicinity. This is pretty common in the Weber Smokey Mountain, and is why I don't use water in mine.

I would suggest some things:

1. Check the calibration of your thermometer (get a temperature reading with the probe in boiling water).
2. Put a thermometer (an oven thermometer will do) in your cooking area, to get a sense of any discrepancies between the lid and the cooking area.
3. Crank up the heat, if necessary (250f is still "low and slow").
4. Experiment with not using water, to see if that makes the heat distribution more amenable to cooking in your smoker.

Now that you have some cooks under your belt, the time is about right to tweak your methods to your liking.