Training isn't wasting time, but you may think of your investment in training somewhat like paying off a loan. If you can make the minimum payments, you'll eventually get it done. If you can pay a little more, over and above the minimum payments, you'll get the loan paid off sooner...but you'll also pay less to the bank.

If you train more frequently, you'll get through the training in a shorter period of time, but you'll also save money that you'd spend on additional training. The national average for students completing a private pilot certificate hovers somewhere between 60 and 80 hours, despite the FAA mandated 40 hours (less for specific schools). If you can train more frequently, you may complete it with less hours, which of course means less expense. Much like paying extra on a loan, flying more than the minimum means that over the course of your training, you'll spend less money.

This isn't always possible, for many reasons. You're absolutely right. Flying is expensive, and the hardest part of learning to fly is paying for it. Some find that taking a loan to finish training is more economical, because they spend less, and sometimes get discounts on rental rates when they put down chunk of money up front (this isn't always advised in aviation, as schools that take money up front and then close their doors, aren't unheard of. Sometimes you can buy time in blocks of say, ten hours at a time, at a discount.

When it comes to flight training, shop around. That's true of most things; it pays to shop around. Look at a school's availability, reputation, maintenance, customer satisfaction, instructor experience, and if you're considering moving up the ladder and making it a career, their ability to eventually not only employ you, but keep you busy as you gain hours and experience.

I recommend someone fly at least once a week, but I also recommend that if someone is able, they do more. The less you fly, the more time you spend on the next lesson, trying to re-learn what you've already covered. Flying infrequently is a process of moving a foot forward, then three or four inches back, so that your training dollar on each flight gets spent a little like interest...you spend part of that lesson trying to recoup what you lost in the time since you last flew. It's like interest, when you pay that loan; part of your money goes to paying off the loan, but part of it just to paying the bank, and isn't getting that loan paid down. The more you pay in a given month, the more goes toward the loan, and the more progress you make toward paying down that loan. The more often you can fly, the more you can focus on learning and refining your new skills, and the closer you get to that goal.