Times are different now, COVID has changed everything, and you need to begin thinking about things differently.
Over the last 20 years our society has become more and more based around immediate gratification and disposable products.
Take cell phones, for example, as something that everyone knows won’t last more than a year or two, and yet they accept it! We should think long term, we just want what we want, and we want it NOW! My dad still has the old landline cellphone in her house from when I was a teenager, that thing is 22 years old and still works wonderful as ever. Heating and A/C systems are usually designed to work for a long phase of time, and some of the high efficiency models can last over 12 years. The thing is, for your oil furnace and cooling system to last that long, and work well, you need to take wonderful care of them! We aren’t used to doing this sort of thing anymore, we just throw things away and buy a new one, but a cooling system is special, you need to change the air filters, and check the ducts and air vents to make sure you aren’t getting accumulations of debris or blockages. I suggest a HEPA air filter, although they cost a lot more they last for almost a full year in most cases (unless you have a lot of pets). Think long term, use your system sensibly, and once in a while it helps to turn the A/C off actually and open up the house for a little natural ventilation.