The phrase "predetermined schedule" means that the schedule or plan has been decided or set in advance, and it will be followed accordingly. Full definition
Ensured animal diets were strictly followed according to Veterinarian guidelines, and fed and watered animals per predetermined schedule. (livecareer.com)
You should treat this the same way you would treat any other loan that requires repayment on a predetermined schedule. (ondeck.com)
So if you are unsure that you will be able to meet a predetermined schedule on an ongoing basis, it's best to avoid those content formats (blog or news - focused email newsletter, for example). (contentmarketinginstitute.com)