Do I need my fan on when cooking in the oven?

In our Grand Design Reflection there isn't any exhaust fan of either kind. We do have a small window at the back of the stovetop and a max air fan in the ceiling close to where the stove/oven is but that's it. So I don't think it's necessary to use yours. We did change out our smoke detectors though as the original ones installed were going off constantly. They would even go off when making toast when there was no visible smoke. They were ionization smoke detectors and we switched them out with the photoelectric type and they don't go off from cooking anymore unless we truly have smoke in the RV.