Question
Rick,
    It seems to me that the fertilizer people are pushing the  season treatments to much. How much and how often do we really need to add all those treatments to have a decent lawn?  thanks, jim

Answer
depends on what you mean by decent...golfcourse??? better than any of your neighbors?? average?? i can't irrigate during hot dry spells??? etc. and where you live??

i'm in southern NJ.
normally 3 applications of lawn fertilizer w/some weed controls per year is enough to improve your lawn appearance by 90 +%. adjust your mowing height to 2-4" depending on the type turf you have(blue grass, tall fescue, etc.). this will eliminate a lot of weed. lime 2x's per year to raise the soil pH. some people have gone to all organic fertilizers w/no weed control.

for now - in early spring(march-april when daffodils are in bloom) lime w/turf lime and apply scotts +halts TB pre-emergent fertilizer. follow the directions on the bags for good results. this will prevent most narrow-leaf weeds from sprouting. opt for no weed control and just use a fertilizer.

in late spring apply scotts +2 post-emergent TB fertilizer as per directions. wet the lawn lightly just prior to the application to aid the weed control in sticking to the weed foliage(dandelions, clover, chickweed, & other broadleaf weeds). no water or irrigation for 24-48 hrs. after that, if it does not rain, irrigate the area for 15 minutes. opt for no weed control and just use a fertilizer.

in the fall-the best time to do seeding (mid to end of sept) start by aerating(rent an aerator) the areas. then apply turf lime(40 lbs/1000 Sq Ft). buy some scotts TB, Ringer, and/or milorganite lawn fertilizer(no weed controls included) and fertilize as per directed by the label on the bag. seed w/the appropriate mixture for your area(sun/shade mix). keep the area moist until germination starts. back off on watering as the weather gets cooler. always water before 2PM and not on rainy days.
check w/your garden center/nursery if other problems arise.
your lawn should look fine from spring thru fall.

visit a local garden center/nursery to see what they recommend for your area. buy products from them & they should be glad to help you plan your project.

good luck
rick
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