I do most online, but find some of the online setups frustrating. Most frustrating, the Federal Student Loan website. You can't pay a bill on it's due date. You have "schedule" a payment 2 "business" days in advance, and if you schedule it too late in the day (which really is early in the day for those of us on the west coast), it's 3 business days. Holidays don't count.
I had a payment due on Monday, went to schedule it on Friday, on a holiday weekend, but it was too late in the afternoon, so it was not applied until the following Thursday.