For traffic in general this increases the number of lane changes and merges, increasing risk and slowing traffic further. Depending on location it may benefit by using more of the road surface (and alleviate problems further back) or may cause problems off the freeway at the local exit either due to greater traffic at the intersection or the freeway queue backing up into surface streets. (Or both.)
It should also be noted that this is an illegal maneuver in some US states. I presume Waze doesn’t suggest it in those states.
I imagine the Nash-equilibrium of this pattern if more people does this is that there is blocked traffic on the highway between the ramps and also on the ramps.
There are two parallel roads between my home and office and google likes to tell me that they will take the same time. One goes though about 10 stoplights in busy retail areas, one goes though about 5 stoplights in quiet industrial areas.
On average both roads might get me there at the same time, but on a unlucky day the busier road may cost me 20 minutes. I always take the other path
This strategy, if followed by enough people, massively reduces traffic stress. It may also reduce travel time, but honestly the difference is likely just a few minutes each way.
Yes, I've driven in cities that play by the "we are in it together, let's work together to get us all out", and cities that play by "any advantage I can get regardless of the cost to others".
Problem is, once enough people start playing the selfish game, the equilibrium breaks and everyone has to go selfish.
that's how you kill a society. Kill the social contract, the care for your fellows, one form of interaction at a time.
Generally I also prefer to stick to more major roads unless there's a major time savings (E.G. >= 5 min, this is part of 'how aggressive' you propose) or accident.
The other aspect of aggressive would be the relative cost for 'unusual movement', such as (legal) U turns, cutting across on small side street connections rather than a major intersection, etc.
It has sent me down some interesting roads though.
I'm pretty sure that isn't even legal, at least in the state of Washington. I rarely go that way, so help me out here Seattle-area Eastsiders, but a lot of folks used to do this on eastbound WA520 at 108th in Bellevue, to the point that there at least used to be a sign at the bottom of the exit ramp saying (in much fewer words) no, you can't get back on the freeway by going up the entrance ramp. (Sorry, street view doesn't show the sign that said, IIRC, "no reentry", so I could be imagining it.)
My theory is that Waze must model what maneuvers are possible/easy based on other drivers in the area. So if you live in an area with more aggressive drivers it assumes those maneuvers are easier to do.
I also wonder if they kind of "round robin" routes so not to cause traffic?
Anecdote: A couple years ago, while driving into Toronto on the 401, we hit some traffic as always. Waze told me to get off at the next exit which I was fortunately right beside, so I assumed it was going to route me around the accident and back onto the highway after it cleared up. What it really did was take me up the off ramp, do a U-turn, and get back onto the on ramp to gain about 700m of distance from where I was before. It theoretically saved me 5 minutes of travel time, but it only really moved me a few dozen car lengths ahead.
Their wealth of real-time and historical data is certainly beneficial, but it also causes some truly bizarre navigation now and then.