I prefer to test our abilities in a multitude of situations, but we shouldn't be aware, necessarily, of what we're up against, except in a few situations. For instance, players often have a small amount of notice if they're gonna go up against, say, undead. They can equip themselves to have some measure of preparedness, at least in some occasions. Sometimes something will pop up unexpectedly, so it's not a hard-and-fast rule.
Ultimately, you're the one using the data you're collecting, though, so throw whatever you think will be most useful against us for your testing.