Most exercise and training regimens recommend focusing on your core two to three times a week with ample rest in between. The best time to work on your abs is post-workout. You should complete a variety of exercises rather than just one form, like sticking to just crunches. Varying your movements will keep your muscles stimulated, burning off more fat. If you’re not adding a lot of resistance during your workout, you can do abs every day if you wish. Even so, you should be changing exercises to prevent muscle imbalances. To improve your mobility and flexibility, resistance bands are another great choice. However, you should also allow ample time to rest and heal at varying intervals.