The age old question of how many meals you should eat per day. Should you eat more frequent small meals per day or should you eat less frequent large meals per day? As always, it depends.
The more important thing to focus on is the total calories consumed. If you're trying to lose weight, you have to make sure you're at a calorie deficit, or eating less calories than you're burning. If you're trying to gain weight, you have to make sure you're at a calorie surplus, or eating more calories than you're burning.
My personal opinion is to find an eating schedule that fits your lifestyle. The easier something is, the more likely you're able to stick to it and sustain it. If eating 6 small meals per day works for you and you're able to stay consistent with your calorie intake, stick to that. If fasting for 18 hours before your first meal fits your work schedule, keep doing that.
There will always be different routes to success!