(1) Pre-screening/qualification/bucketing
(2) Phone screens and online interviews
(3) On-site interviews
Each phase takes N days. The hand-off between each pair of phases takes time. Phase (1) has the built-in lag of you sending something and it getting to the top of someone's pile. Phases (2) and (3) involve coordinating schedules with you and with interviewers. Phase (3) involves making sure the whole hiring team is available to interview you. All three phases may involve a group decision-making exercise of some sort.
If you budgeted a week to each of these phases you wouldn't be too far off.
If you need the process to go faster or fit your schedule, ask! It's a sellers market, and an employer that can't show some flex (or at least talk reasonably about their constraints) is sending you a valuable signal.
Days = business days. Weekends can stretch things out. Ideally at most a month from resume submission to chair-buttocks contact.