Daily.
If you do it daily, you are less likely to forget. Muscle memory of mind and body helps. The power of ‘activity batching’ helps.
But is every day too much? To write every day? To ‘get fit’ every day?
No, it’s perfect. With your writing, some days are knock out the words. Some days are close editing. Some days are working on a pivotal scene. With the gym, some days are CV intensive , some days are strength, some days are working on an injury or mobility or technique.
Daily gets the right things done.