Things easily found are easily lost.
Two commonly questions asked when embarking on flight training are "How much will it cost?" and "How long will it take?" A good instructor anticipates these questions and most of us have an estimate of the time and money required. My answer is pretty conservative (read more expensive) and lately has varied with the price of avgas, which last I checked was hovering around $4.70 per gallon in Oakland.
It's perfectly reasonable to want to know how much time and money you'll need to spend to become a pilot, get an instrument rating, or learn to fly a multi-engine aircraft. What some people fail to appreciate is that the answer depends to a large extent on them. An exact figure and schedule can't be given because teaching a person the skills required to fly an aircraft is not an exact, scientific, or repeatable process.
Some instructors are more skilled than others and some teaching approaches work better than others. Good instructors try to create a logical progression of learning opportunities and tailor how they present the information based on the student's learning style. But how people actually internalize and retain the knowledge and skill is a bit of a mystery.
The FAA sets a minimum number of hours of flight experience and instruction that pilots must log before being eligible to take a check ride for a certificate or rating, but the figures are far too low. The regulations may require a minimum of 40 hours of experience for a private pilot, but the national average is more like 60 to 80. The minimum number of hours for a sport pilot certificate are even more ridiculous, but don't get me started on sport pilots.
A bunch of variables can throw a wrench into even the most carefully crafted flight training plans. These include bad weather, unexpected aircraft maintenance, competition with other pilots for training aircraft, and either the student, the instructor, or the designated examiner getting sick. Add a few other variables like the student's work schedule, family obligations, and vacation plans and it's a miracle that anyone ever learns how to fly. Oh, and don't forget Temporary Flight Restrictions that can crop up unexpectedly and ruin an otherwise productive day of flight instructing.
If there is a secret to successful, efficient, and economical flight training, then it starts and ends with the student's desire and dedication to learn. It's not about outside factors, though they can certainly hold you back. It really is about applying yourself. Most anyone who wants to fly and can find a way to make the time and make or borrow the money, then read, study, prepare, observe, and practice, can learn to fly an aircraft. I said almost anyone. There is about 20 to 25% of the population that, for various reasons, is not cut out to safely fly an aircraft, but that's a topic for another day.
It's inviting for a potential student to think "Gee, Acme Flight Academy can teach me how to be an instrument pilot in 10 days. If I could just get away from the office and concentrate on flying all day without interruption, I could get my instrument rating and then I could fly whenever I want." I've flown with pilots who have undergone accelerated training programs. I myself have done some accelerated training and it can be useful if you approach it correctly. The downside to these programs is summed up by a Woody Allen joke that I'll paraphrase.
I took one of those speed reading courses and I read War and Peace in four hours.
It's a book about Russia.
While the promise of intense immersion training is attractive, my experience is that over time this approach is often ineffective. Quite simply, you may learn enough to pass the check ride, but have you acquired the experience you need to fly safely? If you return to a busy work schedule, fly infrequently, and don't apply what you learned, all that knowledge you crammed into your head will evaporate faster than a puddle of avgas. The FAA calls the tendency to forget what you have learned a lack of currency. Simply put, "If you don't use it, you lose it." Currency is particularly relevant to the world of single pilot instrument flying, which I liken to riding a mountain bike and playing chess at the same time.
My focus is on training pilots to fly safely and work efficiently with ATC. My opinion, based on experience, is that learning to fly takes time and there are no lasting answers available in 10 days. I don't begrudge the schools that offer accelerated training. I often end up flying with the people they have trained, a few months down the line.