Scotts Miracle-Gro

I have spent so much money on regular Miracle-​Gro for the flower beds, the blue crystals in small plastic bags you dissolve in a sprinkler can. And on the lawn fertilizer by Miracle-​Gro. All to very little effect. Why?
I follow directions carefully. And this stuff is not cheap. So why doesn’t it work better than say cheaper triple 16 standard fertilizers? Yeah, the tv commercials look great, but not in my family’s yard and my wallet !!
J bought lots of the new clear plastic boxes at Costco of the lawn seed and growing medium, watering most mornings and evenings for weeks, with minimal Poor results. Maybe six at $ 30 each.
I also bought a new plastic 2wheel spreader, model 76 232, at over $ 50 at Home Depot. It has a tiny 2inch bottom motor and a tiny rear door, that will not close, so you waste new dry granular fertilizer leaving the lawn, all the way up the driveway ! I don’t know what professional gardeners use for wheeled spreaders, but I think the ¼ inch slots /​holes on the bottom are too small. My new model 76 232 would not handle soluble powder, $ 5 for 50lbs, gypsum for our sticky Silicon Valley clay soil. I am returning it, as fortunately, Scott does have Excellent polite, multiple contact options Customer Service. Home Depot says «must have receipt», unlike Costco and Nordstom.
I borrowed the neighbors like new but old Scott 3000 spreader with the axle, long Orange mixer, but it also (.small exit holes of ¼ inch?) can not handle powders like the soluble powder gypsum, nor could it handle new dry granular Bandini 15−15−15 lawn fertiluzer !!
I have Dad’s old metal Scott’s, and totally bottom hole rusted, 2 wheel spreader in the shed, of no use, but he won’t let me scrap metal recycle it.
Guess I will go to a professional gardener supply co., like the one at Foxworthy x 17, or just south of Fry’s in Campbell and see if they have functional quality.