If we spend just 2 minutes (erring on the side of caution) looking at apps - especially when we are drawn to our phones when triggered by notifications - we could be spending 2 hours a day dragged away from the task in hand and have our attention and flow interrupted.
Notifications are counterproductive. Claim this time (and attention!) back for your mental wellbeing and put your phone on airplane mode for at least an hour a day. Your brain will thank you for this.