iPhone 16 Pro to iPhone 17 Pro with .5 Tb of data

Not a problem but an observation. Started with quick transfer and estimated time 7 hours. Read in community that transfer would be much faster with UCB-C to UCB-C cable. Restarted transfer with cables and time says 5 hours. But noticed that new iPhone was charging off of old. Attached magsafe charger to one but other was not charging at all. Restarted from scratch and could not get fast transfer to restart. After several tries finally got transfer to start but estimated time is 2 days! Finally restarted with both 16 and 17 connected to individual powers. Time now says 5 hours and and when i checked after 4 hours estimated time is 1 minute.