Grading rather than improving

I talked too much today. I had back-to-back 75-minute class meetings, first of CS222 Advanced Programming and then of CS315 Game Programming. Both times, I spoke almost the whole time. I would much rather have had structured exercises to help teach what I wanted to show. It wouldn't have been that hard to set them up, just an hour or two each of setting up a template project that demonstrates what I want to show. I don't have an hour or two for each meeting for each class. I have filled my allocated class time with grading. This is partially due to the new grading system I am using. I'm having a lot of back-and-forth with my students. Turns out that getting them to mastery is a lot harder than giving them partial credit. I believe it's bearing fruit. But it's also taking all or more of the time I can give to a class. 

I am not sure what the path forward is. I will do less grading later as both classes move from individual lessons to large project integrations. Then, however, it's too late: we will have passed the point in the semester where a strong introduction is better than 75 minutes of my talking.