Lengthy wait, mysterious behind-the-scenes procedures, non-standardised interviewing procedures (some hiring managers do two interviews, some do only one, some fully virtual, some in-person). The hiring managers keep you in the dark, and while some hiring manager pick candidates on the whim (based on personal favourites or who is the most convenient for their hiring deadlines), others take the full 2-3 weeks period to interview all candidates in a fairer process, and proceed to reject you after this despite telling you earlier on that you were the top candidate.