Spritzing on fragrance takes just seconds and makes you feel instantly more groomed and attractive. However, it shows good manners to avoid applying fragrances just before getting into enclosed areas like meeting rooms, airplanes, public transport, etc. You should also apply fragrance lightly if you work in close proximity to others (as a doctor, trainer, hairstylist, etc.) Remember there is an "olfactive fatigue" effect with fragrance where you become desensitized to the scent you are wearing, so it might seem light to you but very strong to others. This is another good reason to rotate your perfumes because both you and your entourage can become anosmic to your scent, which can lead you to unwittingly wear too much.
Since perfume concentrations and pump nozzles vary, there's no rule of thumb about the number of spritzes. Reapplying small amounts throughout the day rather than a huge amount at once will help you avoid the effect of creating a large fragrance cloud around yourself. I think it's much more alluring to reserve it for the person leaning in towards you.