I adopted my 2 greyhounds from RGT when i was working 9-5, they were fine as long as the dogs had opportunity to toilet every 4hrs and i could go home in my lunch hour. They'd have a walk before/after work. I'm home more now and they generally still sleep till about lunchtime go out to loo and then sleep again till its time for dinner/walk then more sleeping. I prefer having multiple dogs, but know plenty of others with 1 in similar circumstances, some do leave them the full 8hrs & while mine would be fine with this i don't feel its good for them longer term as they don't drink properly in order to avoid toileting.
I have a dog walker now that visits the days i'm at work as i can't get back and they just go out in the garden rather than a walk, mainly as i have 3 dogs so it would be too expensive and 2 of them aren't the easiest to walk so prefer not to entrust that job to another. Dog walker is also handy for days out and as she has a key i can always ring her if we get held up to do another visit.
I think you have to pick the right dog/breed for it to work, some need more human company and physical & mental stimulation and i definitely wouldn't get a puppy/youngster as they all need a lot of input to train/socialise.
I can understand why some rescues prefer not to rehome to full-time workers as there is a greater risk it won't work out, Though i'm glad some are able to consider each case individually.
Would bare in mind that dogs are a big tie, always on a timer when your out & have to go home to see to them & if your at work 9-5 its not really fair to then spend the evenings out too . What to do with them for trips away as its costly to board. They are expensive to keep in general, if you don't skimp on insurance cover & often costs that aren't claimable.
Its easy to imagine nice dog walks not the cold, wet walks in the dark or when your not feeling well (luckily for me greyhounds generally can manage with a short walk & aren't keen on cold/wet either). Summer seems like great time to be out but its often too warm for dogs in the day so its early mornings/late evening walks