Am I also following that after 3 weeks or so, you can tell no difference or advantage of your own roasted beans versus store bought?
Freshly roasted beans practically boil as hot water is added to start the brew as they release their CO2 gasses. That's called the "bloom." Those gases carry the flavors into the hot water, and the flavors taste sharp and "alive" when you sip the coffee.
Freshly roasted beans last about three weeks before they go "flat." By then they've off-gassed their CO2, kind of like a soda does after it has been opened. The flavors are still there, but taste more muted or muddy. The bloom changes from big bubbles to smaller bubbles to practically no bubbles the older the bean is since it was roasted.
Freshly roasted beans, once ground, go flat in about 12 hours. That's why you only grind what you need for your morning brew. When I give roasted coffee as gifts, I always ask if the recipient has a coffee grinder. If they do, they get freshly roasted, whole beans. If not, I grind it for them and know they won't recognize the difference, except the base flavors will be better than what they are buying at Costco, Starbucks, the grocery store, etc.
Store bought beans will have a "sell by" or "best by" date, and it can be up to a year or more down the road. Those beans will be flat as heck. Rarely will you find a "roasted on" date on a commercial package. The exception is local commercial roasters. They usually have a "roasted on" date printed on the package.
Older beans are good for making cold brew and adding extras to your coffee, like Irish cream.
Roasting coffee is like smoking meat. When I first started smoking, I couldn't taste the difference between the different woods. As my experience developed, I could taste if something was smoked with hickory, apple, mesquite, oak, etc. The same kind of thing happens with roasting coffee. Your taste buds slowly develop the distinction between freshly roasted and older coffee. I notice it when I visit friends who throw on a pot of coffee made from store bought beans. Not only were the beans probably sourced from commercial, high volume, mechanized farms in Columbia or Vietnam, they are beans modified to grow fast, typically at lower altitudes. The coffee lacks character, but still tastes fine with Irish cream or whiskey!