I've been searching a software like that for a long time. Creating timetable by hand (and brain) seemed the only possible way for me to solve our problems with different groups and classes. E. g. you have 3 Classes in a year but 4 groups in several subjects that consist of different amounts of pupils each. And eventually I mix up two different subjects like mentioned above.
But after thinking a while how to create these several groups, namely to create a single subject for any possible constellation, I managed it, step by step.
It's really great to watch the software working step by step.
At the end I economized 25% of my usual time to create it.
Next time I'll save even more, I guess.