Wine glasses are designed for different varietals and for different reasons. Is it necessary to use the “correct” glass every time? No. And probably not practical. However, there are a couple of guidelines that may help you enjoy your wines more.
A larger glass is always better, regardless of a red or white wine. White wines typically do not need as large a bowl to aerate, but it doesn’t hurt. It is unfortunate when wines are tasted and/or served in a small glass, because the aromas are stifled. Red wines especially need bigger bowled glasses so they can be agitated more to open up, stir the aromatics, and warm to the occasion.