A bit of caution before you proceed: I am quoting Amber’s words - “just because you can doesen’t mean you should”.
What was your power zone distribution when you do 18 to 22 hours of riding? I can only assume that most of them would be in zone 2 and you did almost little to no high intensity. As volume increases, your intensity decreases and vice versa. Be warned that high volume plans have a lot of intensity and I personally would not reccomend anyone to follow a high volume plan. Speaking from personal experience, I lost motivation to train after completing Sweet Spot base high volume 1 as it was just too much for me. I usually ride around 6-9 hours per week but also occasionally do 20 hour weeks with mostly zone 2 riding.
Last year, I did some ~ 17 hour weeks while following a low volume plan and it was certainly difficult given my life obligations. 3 days of interval training followed by some long rides during the weekdays and the weekends were not really sustainable for me.
I don’t mean to discourage you but would reccomend you to make sure that you meet the strength requirements (Strength Training Calculator - TrainerRoad) and ensure that you stay consistent while following a plan and that might mean choosing a lower volume plan and adding endurance rides on top of it. If you are consistent and can hit your targets, then feel free to add more volume.