I am a Master Instructor with the ATA so I figured I would chime in on this one. I'd like to start by saying all ATA schools are independently owned and operated so the curriculum's content and the way it is taught at one school can be radically different from another school, even though they both may be ATA schools.
In saying that, your school seems to be using a method of block teaching. Block teaching is where more than one rank learns the same form/material during a particular testing cycle (the 2 or 3 month period between one belt test and another). Some "blocks" in this teaching system incorporate just a couple of belts. Ours, for instance, blocks the white, orange and yellow belts together. They rotate through the material for these three belts and when a student has completed these 3 belts they will have done all the material required by us for the completion of this program, although some people may have learned this material out of order. Some schools create larger "blocks", like the one you are looking at. There is really no right or wrong answer as to how the material is presented. This is based on personal preference and what the instructor in charge thinks is best for his students.
When it comes to learning partial forms, there are reasons for that as well. Some schools don't teach full forms because they are more interested in other aspects of training and feel that lowering the memorization requirements can help in other avenues of training. I know of schools that feel that technique is better served by working less on form memorization and more on quality of individual movements. Some schools may have more of a focus on self defense or sparring and that could be a reason for less emphasis on the memorization of forms. This, again, is based on the owner of the school and what their goals are for their students.
There is really no right or wrong way to do these things. You just have to look at the school, it's instructors and students and decide if it is the right place for you and your family. If it is, I wouldn't be concerned with these issues and I would focus on training hard and doing your best at whatever material you are working on.