The way you toast bread can depend on personal preference and the type of toaster you're using.
Traditional pop-up toasters generally toast bread on both sides simultaneously. When you place the bread in the toaster, it lowers the bread into the toasting slots, toasts both sides evenly, and then pops the toast up when it's done.
On the other hand, if you're toasting bread using a toaster oven or a grill, you might need to flip the bread manually to toast both sides evenly.
Ultimately, it's up to you and how you like your toast. Some people prefer to toast only one side, especially if they plan to use the toast for specific dishes like French toast or bruschetta. Experiment with both methods and find what suits your taste best!