Could definitely use a better structured interview.
1. HR call with some quick tech questions
2. Pair coding for 1 hr
3. Final round which includes 3 tech rounds and 1 behavioural
Firstly, you should make the first a few rounds more difficult than the last to filter out unqualified applicants, so as not to waste 4 hrs for both sides.
Secondly, yes the final round lasts 4 hours. While this arrangement might be appreciated back when interviews were held in office, it’s quite stressful given and could be easily bromen into separate interviews now that everything’s done remotely.