I combine science, history, writing, read alouds, latin, bible, memory work, art, and music. In the lower grades all that they do one on one is math, phonics, english and penmanship, the rest is grouped together. Although this coming year I am going to teach my 9th, 8th and 7th graders together in english using R&S, because they all need the review.
As they get into the upper grades I try to keep them together as much as possible too because some things are more fun in groups, such as experiements. Pretty much by the time mine are in 7th they are working independently.