Which is better 1-60 minute walking session or 3-20 minute sessions?

A little bit of background - I am 6 foot 333.1lbs, I am on a journey from 350lbs to 200-220lbs.

I have pitiful motivation and I do not sleep well (the bad sleeping is due to Tourette’s and ADHD)

But I am tired of being fat and not able to walk up a flight of stairs without being winded.

I am working on getting my sleep routine better and waking up early, I leave for work at 7:45, and I try to wake up around 5 am, do some reading or studying before I have to get ready and leave.

My wife has recently purchased a walking pad and I started using it today on my lunch. I walked a little over half a mile in 20 mins (the speed was set at 2mp)

But with my limited time on lunch, I could manage to do 20-30 mins on it every day but I’d like to try and walk for an hour a day minimum.

Obviously I should just do whatever I can, but I am just curious, is there any benefit to doing one long session in the morning or night for an hour, compared to splitting it up, 20-30 in the morning, 20-30 on lunch, and 20-30 at night?