Your Smart Time percentage represents the amount of at-home charging that occurs during the window you specified when registering with Xcel Energy. It is calculated by dividing the amount of energy your vehicle consumed charging at home during your WeaveGrid schedule, by the total energy that you consume charging at home over a given period.
When you plug in every day, as recommended by Tesla, you can better maintain your battery health and increase your chance of having an optimized charge.
You can increase your 'Smart Time' percentage by plugging in whenever you come home, and by minimizing the times you override the optimized schedules generated for you.