Well, American recipes are pretty much the same, if they are domestic type cookbooks. Most of our Canadian cookbooks will have the metric measurements and the conversions. You have to remember that 1 cup of flour by displacement in a measuring cup is not at all the same thing as eight ounces of flour by weight even though one cup has 8 ounces. Heehee, you also have to remember in any of the larger recipes that if the cookbook is American, their quart is only 32 ounces and ours is 40 ounces.
Even though there are ways of making subsitutions, I would tend to buy the product called for.
Also if the recipe calls for 1 cup flour, it doesn't mean 8 ounces by weight and vice versa.
Personally, I stick with whatever measurements are called for in the recipe. I weigh flour and such for commercial recipes and measure for domestic recipes. Otherwise you would have to take all of your regular domestic recipes, weigh out the common measurements and convert and then put all of the changes on the recipe. I find this a lot of work for nothing. An accurate baker's scale is extremely expensive here in Canada, you cannot just use a standard kitchen scale, they are not calibrated or accurate for this purpose.
It is true that weighing ingredients is the most accurate way and this is why it is the method used by commercial bakers. But for regular recipes out of regular cookbooks, I really don't see the slight variance as a problem. The recipes are written up to take this slight variance into consideration.
So your first clue that a recipe is commercial is when they call for 4 or 8 ounces or such of flour. When you use European recipes, they use some measurements that we do not use here. The Australians have slightly different cup and tablespoon measurements.
Hugs Squirrelly Cakes