If you don’t have an ax or a saw, you might “cut” a tree down by building a fire on the ground around its trunk. Fire is a powerful tool, but it’s not naturally a precise tool, so you could end up with a lot of ash and not much tree! An ax, on the other hand, is very precise. If it’s sharp, it makes a cut at the precise point the sharp edge strikes the wood. But it is not easy to use with precision. It’s difficult to hit the exact same spot many times swinging an ax.
A saw is also precise, but using it with precision is not difficult. 
Once you get a groove cut, maintaining that precision is just a matter of keeping the blade edge against the wood and pushing & pulling saw steadily and evenly. Mostly, success means not trying too hard.
But an ax will remove more wood with one strike than a saw will with many repetitions of pushing & pulling. At least, unless you have a really big saw!
With wood, then, it matters both what tool you’re using and what goal you have. As with wood, also with music.
As was discussed in my post When Hard is Easy, the easiest way of doing things is the way with the most effective processes (not necessarily the way that feels easiest!). The RNS Practice Stages explained in that post is a very effective framework. Where there is flexibility is with Spotfixing.
One + one
Perhaps the most useful tool for spotfixing is One + one. This is because it is great at fixing pausing and stumbling spots. These are the most common problems. In it’s basic form, it means one measure (One) + one beat (one), as shown in the example below. “One beat” means whatever happens on the downbeat.
The problem being corrected is pausing before the first beat of the 2nd measure.
To use One + one, play without pause from the beginning of the first measure through the downbeat of the first beat of the following measure. In this case, the RH plays E and the LH plays an A minor chord, but then stops without playing the X’d notes or any notes after them.
Be sure to remember the purpose: To correct the pause by playing repeatedly without any pause.
The Spotfix is complete when the One + one part has been played at least 15x, and passed the 3x Test.
Stops
Stops is another tool, useful for both problem spots and problem passages. Sometimes, a “spot” is not really a spot, but a passage. A passage is a long string of notes without a clear break. You have to master passing through it! Stops breaks up the passage—like rest stops on a hike up a mountain. You’d want those stops to be relatively often, so you don’t get too tired before you get to rest up. That way you’ll stay fresher, never get too stressed out and notice more things along the way.
This is what we do in the music. The excerpt below is from Chopin’s Nocturne in Ab, Op. 64, No. 3. The passage over which I have placed purple stars is one long slur spanning over 10 measures. There are patterns within the passage, but Chopin is after one long flow of movement—one long melodic phrase. This is something one has to build up to, and practicing using stops is a great way to do that.
To use Stops, you have to choose places to stop. I generally use equal portions, but they are not necessary. The stars are placed every two beats. This is where I would begin, as follows:
- Begin at the beginning of the slur (m. 3) and play to the note under the first star, stopping on that night. 3-5x
- Play with a singing tone and flowing legato.
- Before beginning, think through the entire segment and any hurdles it might involve.
- Then begin on the note under the first star and play to the note under the next star, repeating step one. Continue from star to star until having worked through the whole passage.
- Repeat the above, with the stops changing so as to gradually increase the length from one stop to the next. Following is a good way, but not the only way:
- Stops = the first note of each measure.
- Stops = every other star.
- Stops = first note of every other measure.
- Stops = every 3 measures.
- Stops = every 5 measures
- No stops
You can also keep the stops the same, but decrease repetitions of each segment.
Rearranger
This is basically stage one RNS practice with a twist. The twist is that you don’t practice phrases in correct order. Practice them
- In Reverse – last phrase, next to last phrase, next to next to last phrase, and so on.
- Leap Frog – a & c, then b & d, then c & e, and so on. Also in reverse.
- Forward Then Reverse – first phrase, last phrase, 2nd phrase, next to last phrase, and so on.
This is good for variety and also for memory. You have to think about where you are in the piece when play phrases out of order and that’s great for learning their real order.