I'm aware that this is a common question and one that can be quite situational, but I have a few specific questions regarding nuance between these two pronouns for "I".
jisho.org describes 俺 as "Male term or language, sounds rough or arrogant". However, based on my knowledge, I'd say that this is the most common pronoun among college and older males (please correct me if I'm wrong, I may just watch too much anime where the characters are over-confident). While I understand that it may sound too colloquial in a formal situation, is 俺 really as arrogant as a dictionary definition makes it out to be?
In a similar vein, would 僕 sound overly submissive or weak for an adult male (I'm personally a 20 year old college student), or would it just sound more humble and polite (still colloquial, though)?
Last, do people change their pronoun based on the situation? For example, would an adult use 僕 typically around friends/coworkers, but if it's necessary to take a leadership position briefly or make a strong point, switch to 俺 to be more assertive, then back to 僕 when the situation gets more relaxed again?