Look into "staggered nutrient addition" (commonly abbreviated as SNA). There is a link to some info in the stickies. It, or at least some staggered variation, is the preferred method these days.
It doesn't need to drop ten points a day, but you don't want it to stall out later either. Is your temperature at a good level for your yeast? Did you pitch enough yeast, and were they rehydrated/started properly?