If the package you want isn’t offered, when you’re ready to buy it, you can ask your tutor/teacher to create it for a few minutes, then you immediately buy it and finally the tutor/teacher removes it and restores the previous configuration of his/her offer. In my experience, only one package can be created for a given duration. To go round this limitation, a tutor/teacher can create packages on demand, listing the discounts for all the packages that he/she is willing to offer. This is what I do, and it works pretty well.

I think a teacher can be very flexible with time / duration of lessons: you can just ask it.

It depends on what a teacher wants to propose. For exemple I only offer package of 5 lessons because I think that is a good compromise. As a student I wouldn’t pay for 20 lessons immediately , but it’s just my opinion.

You should ask ask this to your Italian language teacher,

Teachers decide what to offer. The choices are no package, 5, 10, or 20 lessons. Your teacher apparently offers a 20-lesson package. You can politely ask them to offer a 10-lesson package. They may change to 10 lessons, and then change back to 20 after you purchase the requested 10-lesson package.