Flossing your teeth at least once per day is very important at keeping your teeth clean and healthy.
Brushing your teeth is better than not brushing or flossing at all but even when you brush your teeth there still can be food particles in between your teeth as you chew the food and sometimes those food particles get stuck between your teeth.
Those food particles can rot and lead to bad breath, gum disease etc and then can also lead to tooth decay as well.
So flossing at least once per day is needed to keep your teeth healthy.
To keep your teeth clean and healthy and to prevent gum disease you should floss at least once per day between tooth brushing.
Some people including myself floss their teeth twice per day such as after a meal such as dinner and then again before going to bed.
I used to only floss at night before bed and after taking a shower but I started flossing my teeth after I have dinner and then floss between my teeth once again before bed.
I've noticed my teeth are much healthier and have stayed cleaner as a result of flossing twice per day.
I brush my teeth twice per day and also floss my teeth twice per day as well.
As long as you floss once per day that's usually good enough but flossing more often is not bad either.