It is true that in practice, you can't foresee everything that is going to happen in a practical experiment (you wouldn't do it anyway if it was the case). But

It is true that in practice, you can't foresee everything that is going to happen in a practical experiment (you wouldn't do it anyway if it was the case). But it doesn't justify not enforcing clean research practice. If you need to move the goalposts, you can do it, it's call "adjusting the hypothesis". You make a new hypothesis and you test it properly. Sometimes you need to iterate a lot, and you fall into the risk of https://xkcd.com/882/ https://xkcd.com/882/. Which still underlines the importance of having a strict scientific approach.