Physically... unless you are working a dog hard most of the day, no one is providing a dog the exercise they actually can take, or are built for.
Providing tons of physical exercise can result in a situation where you have a superfit canine athlete who... needs tons more exercise. It also doesn't necessarily meet the dogs mental exercise/enrichment needs.
So a dog who for example, goes out for a 5 mile run every day, plus a 2 hour brisk on lead walk around the same footpath, same direction etc etc... Is probably getting less mental stimulation than the dog who goes for two 45 minute pootles around the fields, off lead, interacting and playing ball, stopping for a little training session, home to do some puzzle toys and trick training and the relax in front of the fire with a massive dried deer leg chew.
For some dogs a twice daily walk could actually be hell on wheels - if they're anxious or overwhelmed by the outside environment, perhaps the owner lives on a busy road and the dog finds traffic horrific, then the walks may be doing more harm than good.
I walk my dogs from my wheelchair and we're now down to 3 dogs so they get 20 minutes twice a day, individually, as I don't feel that taking multiple dogs out is sensible, safe or actually meeting their needs.
This is for a pavement walk, we vary the route, the time, the direction, and we stop and play in various places or do a spot of training, whatever we feel like that day. I might hide treats in clumps of grass and then the dogs find them, I might hide a toy on dog A's walk, and then on dog B's walk we track dog A's scent to the toy and 'find' it...
My partner takes each dog out for a run over fields I can't access, several times a week (most days for the young uns, twice a week for Mr Oldiewonk McBlindypants), and thats around 40 minutes of running, pootling, sniffing, exploring the stream and the woods.
Then at home each gets a fun puzzle solving free shaping session most days, plus working on anything we're specifically working on top of that. We do 'free work' in the yard (another enrichment and confidence building activity), and they have lots of food dispensing toys and revolting dried animal parts through the week.
This less rigid routine means if something happens - if I am ill or in hospital, if the weather is vile or whatever, they are not expecting to stick to a routine. SO alterations to the daily plan do not cause distress.
They're all fit and healthy and the youngest is 5, oldest turning 15 this year, so I don't think the lack of multiple-hour romps three times a day or going jogging has done them any harm!