Six years ago, my son did half days public school/half day homeschool...for half a year. After Christmas/Winter break we went to full time. One of the problems is that elementary classes aren't all black and white start and stop times. Special areas and lunch are always at the same time but time in the science lab once a week might be randomly scheduled in the morning when he wasn't there but they were supposed to be teaching him science in the afternoon. Or the teacher might allow time to work on the social studies report/project during writing time. It worked in a general way and he did fine but missing this or missing that or the schedule was changed due to this was too upsetting, we just decided to try full time, figuring that we could go back to part time if that didn't work.
Middle school is easier because each period has a beginning and ending...we always held part time homeschooling in our back pocket as an option during middle school. Only had a problem his 8th grade year with a bizarre number of substitutes and therefore substandard instruction leading to his frustration, but I went in and cleared up all the problems and he was once again happy. I never mentioned it to the school but told my son that it was an option if the situation wasn't resolved.
