There's always a risk associated with everything and that's why I mentioned risk tolerance level as we all can choose what we do with the vehicle, whether we have it serviced at the dealership or if we go through the DIY route. I see having the dealership performing the oil changes at their presence as me playing it safe and not have to go through the hassle of me recording a video of myself with a timestamp and everything during the warranty period of the vehicle so I do not mind eating that few hundred dollar cost of oil changes over that span of time.
Like you said, it also depends on what the time is worth to each individual as well. Some people may have more disposable income and can be doing other work while having the oil changed at the dealership or perhaps they are irritated waiting for it to be finished but it comes down to personal preference.
Quantifying the oil changes, there's a few other variables as well such as:
- Jacking up the vehicle
- Placing jack stands
- Getting the tools out
- Removing the old filter
- Undoing the drain bolt and waiting for the oil to drain
- Pouring new engine oil
- Pouring the used engine oil into an old oil canister
- Transporting that used oil for recycling at the nearest auto parts store
If it's about saving time, it isn't really saving all that much since most of us don't have a two post lift like the dealership/mechanic and we still need to transport that oil to the nearest auto parts store to recycle but if it's about saving money, then yes I would agree. If the dealer screws up the oil change, it's easier to go back and have them fix the issue as they were the last ones to touch the vehicle but I get the point of DIY and then ensuring that the work was done properly.