Pressure angle of involute gears does not exceed 25^0, since
(a) this will lead to unwanted radial force
(b) the number of teeth to avoid undercutting will be very high
(c) no cutters are available
(d) gear will become too small
The question was posed to me during an internship interview.
My question is from Length Of Arc of Contact topic in division Toothed Gearing & Gear Trains of Machine Kinematics