Have you ever had a short delivery date?. I am going to give you my recipes to speed up your theme development, from replacing kint whenever necessary, use and preconfigure shortcuts/live templates in phpStorm, how to use only Bootstrap grid system only, disabling Drupal 8 cache completely, and my most used mixins in SASS.
Also I'll be showing some of my favorite twig tricks.
All the gotchas and experiences that I have been gathering in the last 2 years, at your service.