Race Track Modeling.
I think race track is the longest exercise i spent time on because of first, not be able to click control Z to undo a wrong part I clicked and redoing the whole thing again. This exercise plays around with the faces and doing a lot of extruding too.
I also learn a new tool of creating Deformers > Nonlinear > Bend. This is where it allows the straight track to bend into a curve track.
Reflection: This exercise really thought me of choosing my vertexes correctly and accurately and not to rush on the things I'm doing. Doing it slowly and accurately will help me to save more time rather than wanting to finish it fast but ended up redoing it again and again.