I believe you have a mistake on the last slide. On the first dash where you explain “Be thin” and “the flow deviations will be large” is wrong. If the airfoil is thinner the flow deviations will be lower, while if the airfoil is thicker, then the flow deviations will be higher. So “Be thin (otherwise flow deviations will be LOWER and wave drag will be LOWER)”
I believe you have a mistake on the last slide. On the first dash where you explain “Be thin” and “the flow deviations will be large” is wrong. If the airfoil is thinner the flow deviations will be lower, while if the airfoil is thicker, then the flow deviations will be higher. So “Be thin (otherwise flow deviations will be LOWER and wave drag will be LOWER)”