When I train a new skill (notice I don´t say technique;-)) I do it the following way:
Let´s say I want to get better at my triangle from the guard position
1. If you are a beginner just train the basic mechanic of the move if you already know the move you may want to revisit your mechanic or just move on to step 2.:-)
2. I ask myself what is the most important step to launch a triangle from the Guard. So in my case I would say Guard control is the key to land a triangle (or another submission). Do I have guard control? If not I need to work on it.
3. I try to find out which entries I can do from the different guard control positions. Triangle from Overhook, Triangle from Underhook, etc.
4. Now I play with guard control and the different entries and try to understand when to use which entry while controling my opponent. Usually you find 5-7 entries, maybe three of them are your favorites and you work them most.
5. Now I would roll with some guy who isn´t near my skilllevel and do some positional sparring to get the chance to hit triangle while doing alive sparring. It´s important to have a "weaker" guy because you want to play and not go all out. All out doesn´t help your creativity and learning that much.:-)
6. After doing it you will see that your opponent has different reactions to your triangles. So what you need are combinations of attack and follow ups to the different counters. Go back to your technically work and train these moves then play with them.
7. Go back to your "weak" partner and do alive sparring again now incorporating the follow ups and combinations.
8. Roll with someone of your skill level to see which mistakes you still do and which counters are also available the "weaker"guys didn´t know. Pressure test your triangle skill to see where it fails
9. Go back to the technical stage and make some corrections from the experience you gained from rolling with the guys your level.
10. Go back roll with the strong guys again.:-)
By now you may spent six, seven or more weeks on these skills and you pretty much dont like the triangle anymore..-) That´s great.:-) You still have weaknesses but just call it a day and switch to a new area you want to train. Maybe after a few month or even years you come back to the triangle stuff and work with the knowledge you made over the years. Then you can push it to a new level.
Take care
Björn