A quick meat sauce is a perfectly good thing and we are not here to sneer at it. But it is a different dish from a ragù, and people who try to make the second in the time available for the first end up disappointed without knowing why.
Three things take the time: the soffritto, the browning and the simmer. Skip any of them and you have made the quick version.
The soffritto is not a step to rush
Onion, carrot and celery, chopped very small, cooked in oil and butter over a low heat until they collapse and sweeten. Not five minutes. Twenty to thirty, until the volume has halved and the colour has gone golden and the vegetables have stopped tasting of themselves.
This is the foundation of the sauce's sweetness. Without it you end up reaching for sugar later, which is the tell of a sauce built in a hurry.
Brown the meat like you mean it
Mince dropped into a pan of vegetables will steam in its own liquid and turn grey. Grey mince tastes of nothing.
Take the soffritto out, get the pan properly hot, and brown the meat in two or three batches, pressing it flat and leaving it alone until a crust forms. It should catch on the base of the pan; those stuck brown bits are flavour you will deglaze back in.
A mixture of meats is traditional and better: beef for depth, pork for fat and sweetness. Coarsely minced or hand-chopped is worth seeking out, because fine mince turns to paste over four hours.
Milk first, wine second
This is the step people leave out and then wonder why theirs tastes sharper than the version they ate in Bologna. A cup of whole milk, added to the browned meat and simmered until it has all but disappeared. It tenderises the meat and rounds the acidity that arrives later with wine and tomato.
Then the wine, white or red, simmered hard until the alcohol has gone and the pan smells of wine rather than of spirit. Then tomato, and here less is more: a couple of spoons of purée and a tin of whole tomatoes crushed by hand, not two tins and a jar. Ragù is a meat sauce with tomato in it, not a tomato sauce with meat in it.
The simmer
Stock or water to barely cover, the lid on at an angle, and the lowest heat that keeps an occasional bubble going. Three to four hours. Top up with hot water whenever it looks tight.
What is happening is the same thing that happens in any braise: connective tissue in the meat turning to gelatine, which is what gives a long-cooked sauce that clinging, glossy quality. You cannot get there faster with more heat, only with more time.
It is ready when the fat separates and pools orange at the edges, and the meat has gone from grains to something softer and more unified.
Marrying it to the pasta
Never sauce on top. Drain the pasta a minute early, keeping a mug of the water, and finish it in the pan with the sauce and a splash of that starchy water over the heat for a minute. The starch and the fat emulsify and the sauce grips the pasta instead of sliding off it.
Wide flat shapes, tagliatelle and pappardelle, or tubes with ridges. Thin spaghetti has nothing for a heavy sauce to hold on to.
The other slow sauces worth knowing
Ragù bianco. No tomato at all. Pork or veal, white wine, stock, a lot of rosemary and sage. Paler and, to a lot of people, better.
Lentil or mushroom ragù. The same structure without the meat. Dried porcini and their soaking liquid provide the depth; brown lentils provide the body. It needs less time, about ninety minutes, and a spoon of miso or soy does no harm at all.
Sugo di carne. Whole pieces of meat rather than mince, braised until they fall apart and then shredded back into the sauce. The easiest version to get right, because whole cuts forgive a long cook.
Make it on Sunday
Ragù is better the next day and it freezes perfectly. Four hours on a Sunday afternoon, in a pot that needs looking at every half hour, buys three dinners during the week. That is the real argument for the long version, and it has nothing to do with authenticity.