You are forgetting one thing: The training effect. You will become fitter as you progress which means the workouts will take less time and you’ll be stronger-easily able to do this routine after 2-3 weeks.
You’re mentally holding yourself back. My advice is to trust the process–and try. I think you’ll be pleasantly surprised as I’ve seen this happen many times. The exact ‘rate’ of adaptation will vary, some may need 2 weeks, some may need 4, but I would wager that if you do 1x general strength routine 2x/week for three weeks that you’ll handily complete 2x of the same routine in a reasonable time on week 4.