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Think of them as informational data; each plays a different role, depending on what you’re trying to achieve. For those who are diabetic and need to lower and maintain blood glucose levels, a more strict approach might be best. And those who are just in it for the diet might be able to be a little more lax.
But I think there are some basic standard truths, no matter your purpose.
For example, if you want weight loss, you need to stay under your calories. While we’re all different, going over your calories will result in weight gain while meeting them will maintain weight (neither +/-). Again, we all respond differently.
Think of carbs as a limit not to be exceeded. To achieve and maintain ketosis, your body must burn fat rather than the carbs it wants to burn (carbs are ‘easier’ to process so your body burns them whenever it can). Exceeding your carb macro might - might - reduce your ketosis. Indeed, some folks chose to track Total Carbs rather than Net Carbs as doing so drastically reduces the carbs that can sneak in to your diet when tracking net carbs; total carbs count up much faster so you really have to be on your toes, although after a short while it becomes second nature.
Protein is the one macro (in my opinion) where you should try to achieve it. Make sure you’ve set your protein macro to sustain your target weight (post-weight loss) as there’s no need to sustain your starting weight. And you should be very careful about exceeding your protein macro: excess macros can be converted to carbs and that’s not what we’re trying to achieve.
Now to fats: again, it’s a ‘do not exceed’ limit. And when you’re starting out, you should consider going under your fat macros as that’s where some impressive weight loss is possible. Consider this: your body requires ‘X’ amount of energy to function. This energy can be made from carbs, or fats, or a combination of both. If you really restrict carbs, you force your body to burn fat (the energy has to come from somewhere). And you have two kinds of fat: that which you eat (dietary fat) and fat which is stored throughout your body (adipose fat). Limiting dietary fat results in increased use of adipose fat for energy (you burn body fat). This is more true at the start where you (might) have more body fat to burn. Once you’ve burned off your excess body fat, you’ll have to increase your dietary fat to maintain energy requirements. But in either case (starting out or maintaining), eat enough fat so you feel full. As you go along the trail, you’ll figure out what works for you.
Going over a particular macro by one or two isn’t the end of the world, but routine excesses won’t serve your purposes. Again, we’re all different so one person can go over by a bit and have no bad results, while another might if over by only one. Only your personal trial and error will inform how you react. A good blood glucose/ketone monitor (such as KetoMojo) might be a good thing.
somewhat long winded, but I hope this helps.
Good luck and keto on!