I have done many regimens.
My current pre-quarantine schedule was:
Morning 1x long black at a cafe near the office with a colleague
Rest of work day (plus minus 1 on each item) 2x long black from machine in the office, 1-2x long black with another colleague(s) at a cafe
Home (around 5-6pm) 1x long black
Current WFH schedule is: 2-5x long black roughly every 90 mins.
I enjoy the ritual of making it (plunger) and the warmth. I don't think I get a buzz anymore, but the odd time I do, I love it.
I don't get any noticable side effects, and have gone periods 1-4months without drinking it with no adverse effects.