With any training, you're going to come across some demons. If you're female, this may be a pattern among your menstrual cycle (something I've been researching quite a lot lately). With fluctuations in hormones there and dependent on your own individual symptoms, there may be ways to time certain training at different stages of the month. For example, if you feel slightly lethargic is phase 4, just before you get your period, high intensity training might not be as beneficial as putting in some endurance effort.
I'm a women in the industry but I do not have all the facts and figures. I try to educate myself as much as I can, mainly for my own training and knowledge on my body. If I find that the information is useful to me, then of course I can spread the message and direct people to amazing sources - Stacy Sims, Fitr women and the podcast 'female athlete pod' are amongst the easily digestible source of info that really do inspire me to want to know more.
There's no weakness in your monthly cycle, nor is it a factor for an excuse per say but merely an opportunity to progress in certain areas of training whilst your body is experiencing changes each month.
I have to say, during phase 4 and a mixture of a terrible attempt at a new movement, I think my cortisol levels due to stress and frustration could have sent a rocket to mars. Wall walks were made by the devil.