Quantity: This makes a generous amount of topping. We like our crisp nice and thick. If you prefer a thinner layer of oat topping, you can use a larger baking dish.
Apples: Be sure to use good baking apples to avoid ending up with mushy apples!
Lemon: If you like lemon in your filling, go ahead and squeeze some in (we liked it without!). You will want to add a tablespoon or so of cornstarch, tapioca starch, or sweet rice flour to thicken if adding the juice. As is, the recipe makes just a bit of light syrup that can be drizzled over the crisp when serving, but the juice would add to the liquids.