This is partly a repost of how to train for a jutsu, but also to clear up some details as well.
First, the basics from the book.
Learn Checks are used for learning, and mastering jutsus. They are calculated out as your level + the relevant stat mod + other bonuses from feats, or having 5 or more ranks in the relevant skill.
You get a number of attempts equal to 1 + the relevant stat mod + 1 every 2 ranks in the relevant skill. You have to have at least as many attempts as the jutsu needs successes to even get it, so remember that when your looking at what jutsu to take.
You can take 10, but your not hiding what your doing, though they can be done in remote places to reduce the chance that someone will see you training like that. Taking 10 also requires that you have at least 1 skill rank, and all other requirements.
Because of how the rolls are handled, and that you can cut time in half or more, rolls can either be made before the first training session, or after the first 4 hour block of each check as the minimum time for each success is one 4 hour training block.
Steps for learning a Jutsu:
1. Pick the jutsu you wish to learn and can learn unless a exception is made by the gm.
2. work out all bonuses to the roll(Feats, 5 ranks in the relevant skill, having a teacher, having a scroll, spending a action point(this applies to all rolls made for that jutsu), and any other modifiers) as well as how many attempts you get to try to learn the jutus(level+stat mod+1/2 ranks(rounded down))
3. work out the time needed to learn the jutsu, rank is the number of days needed for each success. That means for each day of training needed you need two 4 hour blocks.
4. make the roll, and based on the result account for the time required. Refer to this table for how the result effects the time spent:
Learn check result Effect
Success by more than 15 Time decreased by three-quarters (round up)
Success by more than 5 Time halved
Success by less than 5 Attempt successful
Failure by less than 5 Attempt unsuccessful
Failure by more than 5 Attempt unsuccessful, time increased by one-half
Fatigue and training
Training can not be done while fatigued. In addition to the greater chance of injury, there is the fact that for the most part your chakra channels are not conducive to training.