Notifications are designed to interrupt you. Every alert pulls your attention away from what you are doing. Instead of checking notifications constantly, schedule specific times. You might check them three times a day: morning, midday, and evening.
During your notification checks, process everything. Respond, file, or delete. Then close your notifications and do not check them again until your next scheduled time. This gives you long stretches of uninterrupted time for focused work.
This schedule also reduces the sense of urgency that constant notifications create. You are not always on call. You check notifications when you are ready, not when they arrive.
Set your notification schedule today. Choose two or three times when you will check. Turn off alerts between those times. Then notice how much more focused you become when notifications are not constantly interrupting you.