Practicing video poker strategy by using a computer program or smartphone / tablet app is far more effective than practicing manually as described in section 7.2. The only real problems that might get in the way of you doing so are that you need a computer or smartphone / tablet and you need the program or application. As mentioned previously, there are several good video poker programs and applications available. They are also quite reasonably priced. If you do not have a video poker application, I strongly suggest you purchase one as soon as you can. You can practice manually for a while until you receive it, so you will not be just sitting around and doing nothing while you wait.
Video poker is a very volatile game, about four times as much as blackjack. In any form of gambling, short-term results mostly depend on normal mathematical randomness (what some might call luck). However, in the long run, results mostly depend on skill. If you play a game with a return of 100.76% perfectly, that does not mean that you will have a 0.76% profit every time you play. The 100.76% is an EXPECTED return. Much in the same way, if you flip a coin ten million times, the expected number of tails will be five million, but it is unlikely you will hit five million on the nose. Actual results will vary significantly from expectations, but the more you play, the closer your actual return percentage will get to the expected return.