Pavel is a big advocate for training frequency. "grease the groove" is just toned down volume+intensity and ramped-up frequency. i think there's a section in Power to the People where he mentions how some Olympic lifters train every day.
i think of it as a manual labor job: you have to work 5 days a week/8 hours a day. your boss isn't gonna say "the optimal work time is 3 days per week/45 minutes per day. any more than that, and you would be overexerting yourself." you just have to get the work done to keep the job and get paid, there is no "this isn't optimal for my body." of course, manual labor isn't exactly the same as heavy resistance training.