If you are answering correctly you will start getting more difficult questions. However, it is not very linear. E.g. you may start at 78 level for Quant (sectional scale rather than our more "customary" of 555-595 for example) and then if you are right, you will get level 80 and if you are right, you will get 81 but you may also get 83 or 77 because the question bank may not have 82 or 81 of that particular question type.
There are also experimental questions and those may be very easy or very hard and not correspond to your difficulty.
In my experiments with GMAT Prep the questions also maxed out at a certain level (not 805 but rather around 655-705) as there were no more hard questions in the question bank, so you should not expect to start getting 805's by the time you reach question 10. It is all a bit complicated but you DO NOT need to worry about it. Just solve the questions in front of you - that's all you need to worry about and you will see a lot more easy and medium questions than hard ones.