Cindi,
There is a huge difference between time of year, and location. I see the original poster is from California. Probably pretty active colonies. Cracking open the boxes and sliding in a patty is actually faster and easier than taking off a top, top feeder, etc. I could probably feed a patty in about 5 seconds.
Now, feeding in Canada, I may actually agree with winter or early spring feeding with patties on top. The trapped heat, the moisture, and the location of the cluster may dictate that top feeding would be the way to go.
But In California, to maximize feeding, it is still best to place the patty directly in contact, if not directly in the center, of the cluster.
Location, location, location...... ;)
Added: And it is also good advice for anyone in SHB areas, to ensure your bees will utilize the patties by placing in the middle of the cluster. Many have found out that patties ignored while on frames of the top box, really is a feeding ground for the SHB. Many suggest now placing in the middle of the two boxes in the center of the cluster to allow the bees to keep SHB in check. Yes, in a perfect situation, the bees would go right up and eat all the patty. But that does not always happen as planned.