An honest note about an hour
For most people attention dips before the hour is up, often somewhere between 40 and 55 minutes. That is normal, not a failure. The timer is there so you stay with the task through the dip rather than switch to something easier, and so the break arrives on time.
The break matters more here
After a full hour, ten minutes away from the screen is part of the work. Stand up, drink some water, look at something far away. The next block is armed when the break ends and waits for you. If an hour is too long today, the 45-minute and 50-minute timers are one click away.