There is a limit of 20 activity-batches that can be loaded into any schedule.
Most people use only 6 to 9 Batches.
It is not a good idea to use lots of small Batches.
The reason for this is that if you have a Batch of only a few lessons then you are not giving TimeTabler the opportunity to work on your data and suggest a priority order to you.
This is because TimeTabler can only prioritise the activities in the Batch(es) that is currently loaded.
So if you have a Batch of only 6 lessons of Year 7 then it will only prioritise those 6 lessons against each other(!) ...but of course you want to know the priority order of all the lessons in Year 7, in order to assign all of Year 7 in the best sequence for a 100% fit.
During the scheduling stage, the usual and best practice is to load a Batch and completely assign all the lessons in it, ...before loading the next Batch and assigning all the lessons in that one, etc.
Most people have one 'Fixed Points' Batch, and then either one Batch or two Batches for each Year-group.
eg. one Batch for all of Year 11.
eg. one Batch for all of Year 10.
eg. two Batches for Year 9: one for the big blocks (which I know in advance that I want to assign first) and then the other Batch for the rest of Year 9, etc.
See also sections D2, D5 in the current Manual.
In this way, you can guide or steer TimeTabler by the sequence in which you load the Batches progressively into the schedule (as explained in Section F9 in the Manual).
Just occasionally, you may need to have Batches that cross Years. For example if you teach in a school where the science accommodation is very tight, you may want to have a Batch of all the science lessons in upper school and then a separate Batch of all the non-science lessons in upper school. In that way you can sequence the batches to give science the priority.
Click here for a discussion of the best Sequence to load the Batches.
See also steps 20-22 in the QuickStart Guide in Section A of the Manual.