That may well be the case we only use light weight interliners in our blinds and never use linings and interlings supplied by someone else.
Please note this is a design decision that only you can make and there are many factors to take into account. including
1. How big the you want the top section (to block/not block light, show or position a pattern on the fabric, how it will look relative to the overall size of the window, what you may want this section to cover - particularly when outside recess)
2. Number of folds ( affects thickness when pulled up,)
The figures given are an example, fewer folds may well be better in your case. Ultimately if we are unsure we would make up a small mockup.
Here are a few images to show you how thick the interlined blinds may be.