Yes, you can. You could do your own organically (which would involve a high expense in terms of stuff) for about $400-800, or synthetically (which really isn't quite so bad as you might suspect if sensibly applied) for about half that. And that's for all five apps.

Your lawn guy is also not applying things at the correct time because your lawn guy is following a standard schedule and does not really know lawns. That's another story.

Twice a year is...well, tolerable, although if I may suggest:

Memorial Day: Organic application, 15 pounds per thousand square feet soybean meal or 20 pounds per thousand square feet Milorganite (more expensive).

Labor Day: Ditto.

October 1 to November 1, when growth slows and cutting is near the end: Urea or any other high-nitrogen synthetic at bag rate to supply 1 pound nitrogen per thousand square feet as a winterizer (it's too late for organics in CT).

The October to November application is for winter survival of the lawn, spring green-up, and to store carbohydrates for spring growth. The date will vary because the weather will indicate when it gets done.

If you want to use a crabgrass preventer, you can use one with no nitrogen (like Halts or Prodiamine) in May, either in your spreader or sprayed if you can get your hose across your lawn.

The lawn care people have to make their boat payments every month, so they try to fit something in.

Also, they leave the most important thing to you, watering. They are hoping you'll make some mistakes and they'll sweep in to "fix" it for you...with more chemicals and expensive treatments.

What kind of grass do you have?

What is your watering schedule? How often and for how long do you water? Have you gotten much rain this year?