Whenever this comes up (and it does fairly frequently) I always suggest that readers got to A Better Route Planner and try out some of the trips they make frequently and some that they think they might like to make in their Rivians. This will grant you some insights as to how long you will be charging, how far you will have to go out of your way to reach a charger and what it will cost. I think ABRPs consumption numbers are a bit pessimistic and so usually dial them down to about 450 Wh/mi.I will add some real numbers here, right from the EA web site:
I've been doing this since I first made my reservation at which time comparisons to trips made with a Tesla were so discouraging that I feared I would be cancelling it. Electricity would have cost more than I'd spend in gas in an SUV and charging added hours. Things are much better now both in terms of the location of stations, their power (rate at which they can charge) and the costs of charging (even though EA seems to still be on minutes even where they are permitted to sell by the kWh). According to ABRP our most common trip will be quicker in the Rivian than the Tesla (X - because of the bigger battery) as a charging stop can be eliminated.
For the moment the main advantage of multiple stalls at a station may be enhanced probability of finding one working. This is an area where EA needs to improve and they know it, have promised to improve things and have done so to some extent. At least, in my limited checking on them, it appears that this is the case and their president has a convincing story. But the other side of the coin is, of course, that eventually vehicles using high rate CCS terminals will be fairly common and the situation we see with Tesla will emerge. I'm sure you all have seen the stories of the infamous stations in California (where BEVs are thickest) with dozens of terminals and queues a mile long. OTOH I've been to stations where I've been the only user.Plus, total number of chargers is not as much of an issue as total number of sites. ... The benefit of having two 350KW units at each site is to take care of the failed unit issues, which continue to plague EA.