20 minutes is a lot of time, add that and at the end of the week you got around 2 hours, that's half a morning per week and close to a whole 8h day of work per month just on the time for standups.
It's not just the time itself though, it's the interruption that prevents you from starting longer tasks effectively.
Can't really account for that, work is not only about summing up minutes on a time tracking tool. There is rythm, there is acceleration, there is a productive state and there is deceleration.
Standups disrupt all that without any real benefit, other than serving as a daily reminder that you better hurry up with what you are doing - which most people don't need.
20 minutes across my team of 12 is not nothing, it's 4 man hours. When I see it communicated in that manner, the sheer pointlessness of these daily meetings is very easy for me to identify.