Seen the schedule on FB now.
The leg to Dingle has Healy Pass, Ring of Kerry, plus numerous other hills. So that'll be a long day from Bantry. He's not doing Slea Head before stopping at Dingle so he'll have the hills on that loop to add to day 3. There's a ferry at Tarbet, last sailing 9:30pm and Kilrush is a provided sleep control. So a short distance day after the leg to Dingle makes sense, and allows for breakfast after a loop of Slea Head. I have the same planned for that.
Kilrush to Oranmore. Personally I plan to push on to the other side of Galway giving a shorter next day to Westport. Seamus may be staying with friends in Oranmore.
Belmullet to Bundoran. I'd agree with this, and it's what I plan to do. But I'm hoping to complete the Blacksod light house loop before settling down to sleep. Seamus schedule has him doing Blacksod in the morning after a sleep at Belmullet. The section out to Blacksod isn't hilly but my god the wind. Think I was reduced to 12km/h moving in the headwind last time, though I flew back to Belmullet surfing the storm.
Dunfanaghy to Greencastle. I had that as a push through to the finish day but stopping a bit short, once past the Mamore Gap and Malin Head, does have its attractions. Plus I haven't looked at ferry timings on that leg. The ferry may dictate a shorter day unless you want some night riding.
Some of it will depend what time of day he intends to start each day and when he needs to have reached his B&B by. The wind will be the biggest determinate of how well or not your plan goes against its schedule.
Seamus' schedule is to give you an outline , you don't have to stick to the same rigidly, but it gives you a starter for 10.
I plan to make full use of the sleep controls provided, you may opt for a different plan.