A convection option is now standard on most new ovens, but it can leave even longtime bakers wondering when to use it. Convection ovens circulate air constantly, eliminating (at least in theory) the hot spots of many regular ovens. This is an asset when you want deep, even color in breads and pastries; crisp skin on poultry; or great browning on roasts.
The circulating heat can be a liability for delicate baked goods such as custards. We test all our baking recipes in both regular and convection ovens. We've found that the required temperature and cooking time seldom differ greatly, though our testers report that they start checking for doneness a few minutes early when using convection.
If the time or required temperature varies in a convection oven, we note that in the recipe; likewise, if a dish is not suited to convection, we advise using a regular oven.