toenails growing faster wearing sandals- help with mystery!

I've regularly noticed that when I am wearing sandals or going barefoot for a few days (usually on vacation) that my toenails need to be clipped within a few days. In my regular life I wear closed toed shoes and rarely need to clip my toenails- maybe once a month?

I always check if my toenails need clipping right before vacation, decide to leave my clipper at home, and then regret it.

Do other people notice this? I have a few ideas as to why, but not really sure

• toenails are somehow being ground or rubbed down inside my shoes normally
• toenail growth is being inhibited by the constant pressure from my shoes
• the increased sensation on my toes from open toed shoes is stimulating nail growth
• actually nothing is different, I just notice my toenails more when I can see them

Would love other people's theories