Problem 2314

The difference between your solution and mine is the following:

You: when there are more than 10000 small steps (< kCarTolerance) you abort the event)

Me: I loop 10000 steps, so there can never be more than those (if the step number reaches 10000, I abort the event)
Each step (after a few initial steps for which I push kCarTolerance) is pushed  std::min(101*kCarTolerance*pow(10,fNumberZeroSteps-2),0.1);

I think that my solution is better.
But every time there is a small step, I send a warning message, while you sent none. This is the difference that causes the big output

I will protect this message with a fWarnPush, which will only be active if the user has compiled with G4VERBOSE=ON

I consider the bug resolved, tell me if you do not agree

I finally decided to protect the excessive warnings under @ifdef G4DEBUG_NAVIGATION. It is a safer choice to avoid you or other users having the screen filled with those messages

I am currently testing your solution. I think, it is also important to reset the fNumberZeroSteps to 0 when a correct step was made. 
Otherwise I got several tracks killed which got stuck a few times but could be recovered after each first consecutive push.

Additionally, I get a lot of the following Exceptions (2800 exceptions in 100000 events):
-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4PhantomParameterisation::GetReplicaNo()
Corrected the copy number! It was negative or too big
          LocalPoint: (10.4,-11.8785,2.6816)
          LocalDir: (-0.695189,-0.625715,-0.353825)
          Voxel container size: 10.4 49.6 19
          LocalPoint - wall: -1.77636e-15 -61.4785 -16.3184
*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


This happens with both my and your solution in 10.7 but not in 10.5.

I do not understand your point: fNumberOfZeroSteps is set to 0 at the beginning of G4RegularNavigation::ComputeStepSkippingEqualMaterials

About the second point, it is just a warning that a precision problem has been corrected (see your LocalPoint - wall: -1.77636e-15 ). You can deactivate the warning: surround it by 
#ifdef G4DEBUG_NAVIGATION
 
Probably it is a good idea that I do the same for the release

I am not sure but I assume, this happened in an area of my voxel model where the material does not change over a longer path (which is quite typical for some medical voxel models), so the navigator stays in the same function call.

Regarding the message: If this is not an issue, it would be good to deactivate it for the next release. As a user, a flooded error log is hard to judge as normal and real errors are getting lost between all those debug messages.

*** Problem 2359 has been marked as a duplicate of this problem. ***

I have added 
    if( fabs(localPoint.x()-fContainerWallX) > kCarTolerance &&
        fabs(localPoint.y()-fContainerWallY) > kCarTolerance &&
        fabs(localPoint.z()-fContainerWallZ) > kCarTolerance ){    // only if difference is big                 
 
This I think would be enough. I will put it in the next release