Hmm, well, yes, it takes a series of visits for your spine to 'relearn' the proper alignment, and they vary according to what the problem is, but normally correction doesn't take years. Maintainance can be lifelong, but it is usally Much further spread apart - think of it as a checkup for your spine.
Both my sister and my husband have been through adjustments, for different problems, and are moving freely and have not "had" to go back, and she's been through 3 *bad* car wrecks.
Some people "Like" to go back because, frankly, it feels Good, like a good massage; some people have much worse degeneration and it takes longer to correct the damage, some conditions, like spondylolisthesis or advanced degenerative conditions do require a longterm and possibly even lifetime committment. Now that my bones have had a chance to set from surgery, I'm looking forward to going back for some correction adjustments to realign years of 'compensation' my back went through. I opted for surgery *only* because the vertabrae was clearly and obviously broken - even I, a complete untrained laymen, could see the break in the X-rays and MRIs.
Every one is an individual and every case of chiropractic care is just as individualized.