It really is important to learn the 'User' custom render settings (and even more so in V6). After all, the developers had to consider all different kinds of images in setting their default render options, so those are set for a some kind of average. Do you want your scenes to look 'average'?

Every scene is unique - so doesn't it follow that to get the best render from your unique scene you should use a unique set of render control settings? And getting faster renders is an added bonus.