Coming from Auto, it won't take long for you to get the hang of manual exposure. For most situations you only need to meter once. Auto and the manual meter indicators move around a lot in response to slight changes in the reflectivity of the subject. If the light hasn't changed, or your subject hasn't moved into radically different light, then you don't need to change the exposure. Matching the arrows for each shot will not improve the exposure.
Originally Posted by brian steinberger
My apologies if you already know that and it seems too basic, but it is not always obvious when moving from auto exposure. I am speaking about negatives. The issue is similar, but the decision making is somewhat different for slides (need to make sure the highs don't blow out).