I find the people effect it more. If you have people that constantly encourage and support you then you're going to do well. Clothing should just be a reflection of your personality, but if it is restrictive, I wouldn't use it as a caveat to under-perform in the workplace. Granted I work in a creative field, so it might be different with more rigid professions. Like an accountant, or a lawyer. I went to an all-boys school with VERY strict uniform rules. If you don't have your blazer, you need to wear a jersey. If it's 30C outside, and you're in the public eye, a teacher can give you detention for not wearing your blazer. It worked well for the environment they trying to create, which brings me to my point actually. A dress code should reflect the environment it's trying to create. For an all boys' school, strict AF uniform rules worked. For a creative workplace, civvies can work fine too. tl;dr Don't wear a onesie to an interview