idk about other countries but most of us indians eat large meals, chew less, then we lie down which affects food digestion. This leads to acid reflux and GERD for many leading to bad breath. Then many Indians brush once only in the morning. This means we go 24 hours without brushing. Even when we brush twice a day, brushing right after waking up is not doing anything as we already brushed before sleeping so waking up we didn't really eat anything in between. I think the right time is 30 mins after breakfast which means morning brush tackles germs accumulated over night + breakfast food stuck in teeth. Then night time brush only has to tackle the lunch and dinner food so it is a good divide.