Just as a guess, stage 4 is to test your ability to understand and apply instruction, and to show your ability to improve with practice.
They adjust the type of flying you do in the sim to reflect your prior experience and how well you're coping at the time. Dunno if they've changed the fundamentals of the process as it's been a while since i did it, but i had a visual departure, into imc at 500 ft, sequence of climbing/descending turns onto nominated headings, a basic configuration change by dropping gear and flaps, then radar vectored to the ils to fly the app, broke cloud at 600 ft and a low level circuit to land.
Thrown in were a few basic maths questions and things like recalling dates i'd previously said, like my brother's birthday etc whilst under the flying pressure. It's all to see how you cope with multi-tasking.
The way i did it was usually to say stand by, finish the flying segment and then when s+l tell them the answer! And i still scraped through! dunno how...........
Don't worry about chop rates, is it gonna help your flying?? No. Concentrate on flying smoothly and working to improve the tolerances that you fly within. You get a couple of goes at the profiles so that's your chance to make improvements. That's what they'll be looking for.
Above all, and i know how easy it is for me to say this with hindsight, but enjoy it! It's a good laugh, with excellent instructors. Have some fun
WBV