Ten seconds to complete the concentric (positive) portion of the repetition. Five seconds to complete the eccentric (negative) portion of the repetition. One set to momentary muscle fatigue. That method is called super slow training.
If you want to follow a method that helps lactic acid build up so you feel the "burn" in the portion of the body that you are training, super slows are fine. If you are interested in getting "bigger" super slows are acceptable. If you are looking for a very elementary, unsophisticated training regimen, I highly recommend super slow training. That is all that this regimen is good for, however. Super slows will not increase your strength. Actually, they have been proven to reduce your strength. Super slows will not increase your performance. They will weaken your overall performance. These are proven facts.
If you want to get on the right track to getting stronger and improving your overall performance you should stay away from super slows training. For that exercise enthusiast, super slows are a complete waste of time.