Been topping for lots of years, but there is different reasons. Some for short-er plants... Other than that, I "top" to double the bud production, triple, etc. Cutting at an angle sounds like taking Clones, to me. I do NOT want one main top cola. I want every branch to have the same size buds as the top bud. Some Indicas cannot be topped, so beware. But normally, I top the top at about 3 ft. tall, which does 2 things. Doubles the top growth & slows the growth down, causing the other lower growth to grow faster. About 2 weeks later, I top ALL end growth, causing all of them to double. Now the bud production is doubled. A month later, do the same again, maybe 50 or more "pinches" to the end of the new growth. This will cause stress/hermies unless you have a very good balance of soil- a healthy plant. I will also top/trim the fan leaves if they block out light. 1/2 one week, 1/2 the next week, letting light in. I can't see paying elect. bills to have the light shine on a fan leaf.