Maryborough has 2 trains in each direction per day. It has 3 daily coaches, but these go to Castlemaine, not Ballarat (there are Ballarat direct coaches but these run very early in the morning or late at night, or only run some days).
If you are looking to go to Ballarat for the day, it becomes a full day trip.
Ararat - Ballarat seems to get quite a bit of local travel, the reason being you can make a return trip just for the morning or afternoon, whether by coach or train. Maryborough and Echuca don't have the same luxury. Frequency is Freedom!