I've had these instances too...well, for the point thing, I guess that could be a GOOD thing, but if it isn't meant to be that way, a bad thing as well.
For icon hopping, yeah. I've noticed if the segment is short I'll hop to the next street over. Also, if I'm driving in a parking lot where roads aren't mapped out too (though, you could add in parking lot roads in the cartouche...but that would take a ton of time to through and do all that...but it be cool), it would hop to the nearest road as well (the nearest one visible on the screen). Those to me seem like bugs. I have a TomTom Car Kit so I know it isn't reception issues, because that will enhance my GPS on the iPhone even when it pretty bad weather conditions.
I just don't think Waze is built to handle off-road conditions...if you are found off-road (well...off-road according to the GPS), it is told to place the icon on the nearest coordinate set that is on a road. I have seen that on shorter segments it has done this if the segment being driven on is shorter than the actual roads.
This could have been done when the person using cartouche that added the roads in did not zoom in all the way...or the road has been lengthened since being built. If the map builder was zoomed out, drawn roads would appear to match up and go along with the road way, but zoom in even more and you could notice very bad imperfections in the road way that could cause your icon to hop from road to road as the GPS tries to locate your 'correct' position. This is why I think it is important that when using cartouche, that newly mapped roads or even old roads be shaped to the actual road, so that the GPS updates your location accurately and so you don't appear to be going somewhere where the GPS isn't expecting you to go...that is, off the road.
I call that, stick it to road syndrome!
Basically, I think that each coordinate point (X Y) that the road falls on, is marked as being part of a road. Now, IF the software was set to fix your icon to the coordinate points that belong to the road, that could explain icon hopping, being that since you are really off-road, and the software knows that, it follows what it knows best...its programming (set rules given to handle a variety of different cases).
If it were that way, it would have to have a rule in there, if you went 'off-road', to put you on the nearest coordinate point that is marked as being on a road segment. If it wasn't a closed system that mean some serious bugs...like, it putting your icon all the way up on a road in New York while you are actually in Texas.
Just a theory anyways. I've always noticed that when I go off on an unmapped road, I'm always put on the nearest road, adjacent to my path. Now...co-incidence that it does this every time? I think not! And in the above case, I think it should be a un-fixed set-up, to where your icon isn't fixed to the coordinate plane. (Yeah...I'm not expert at code, but I understand how it works. I wouldn't be surprised if someone that does know more jumps on here and goes, YOU ARE WRONG! But hey, I'm just throwing in another idea to the loop! And yes...I'm actually teaching my self C++. Go figure!)
Area Manager: Grand Prairie, TX
Waze phone: iPhone 3GS 4.1 iOS