Even there, drug companies often go through the features in a particular order. You start with a range of formulations which you suspect will be safe for human use, you test them to see which are effective, and then you hand them off to a different set of chemists and chemical engineers whose job it is to figure out how to manufacture the doses at scale.
Every part is necessary, but that doesn't mean that there isn't an ordering. Finding something that's easy to manufacture is pretty useless if it turns out later that it kills the patient. On the other hand, a drug that's safe and effective, but is difficult to manufacture is still a viable drug; worst case, you do what drug companies do all the time and charge obscene prices per dose until you figure out how to scale the process.
Every part is necessary, but that doesn't mean that there isn't an ordering. Finding something that's easy to manufacture is pretty useless if it turns out later that it kills the patient. On the other hand, a drug that's safe and effective, but is difficult to manufacture is still a viable drug; worst case, you do what drug companies do all the time and charge obscene prices per dose until you figure out how to scale the process.