Sounds like to me it is not really 4 apps but someone is blending products.
Lets count applications
2 Pre-emergent (fall and spring and often one of those are often split in the south to extend CG control)
1 Post Grassy weeds
1 Post Broad Leaf
Now pick your fertilizer, Iron, Micros and so forth.
It "might" be a good idea to do a slow release in June to get you through the summer but that would be at minimum a 5th app.
I sure would not be putting down a high quality slow release fertilizer @ 1# of N for $45.00