There's very little that's required to move through Shadow.
First, you have to be moving.
Second, you need to be changing the Shadow. This requires that you either add, remove or alter characteristics of the Shadow (or things in it), or have a "Shadow of your desire" so that there's someplace that you're trying to end up.
In addition, you can also pull things through to the next Shadow with you. This will usually be implicit -- your clothes, your horse, your travelling companion(s). Maybe something like "I lead my pursuers through Shadow until we come to a cave by the seaside. Inside the cave lies ..."
But most importantly, if you don't have a destination in mind and don't specify how you're altering Shadow, I've got no idea what you're trying to do. It really slows the game down (particularly with the 1 e-mail a day format), and if I start making assumptions about what the "Shadow of your desire" is, you're not going to like it one bit.
On the other side of the coin is the "too much information". The Shadow of your desire is your destination, not every point in between. Reaching a detailed Shadow that you've never visited before and is not too different from your departure point will usually take about a day, at a somewhat jaunty pace. The Shadows you pass in between need not be detailed. You change one thing -- usually other things will change with it, as you're moving constantly towards the place you want to go -- and you're in a new Shadow. Searching for too much detail on in-between Shadows will only slow you down, as you search out a Shadow other than the one you want before proceeding towards the one you do want.
When walking through Shadow, keep that stuff in mind -- a series of simple changes and a destination make for successful, easy movement through Shadow.
The Royal Way
Now, as I mentioned before, when you change something, usually other things will change too, bringing you closer to your destination.
When you hold certain characteristics to keep them the same, this is called the Royal Way. It's slower, and sometimes cannot bring you to your destination. You may have to pass over a mountain to get there, no matter your route. In that case, keeping mountains out of the Shadows you enter will absolutely prevent you from getting to your destination.
In any case, the Royal Way slows things down. You rule out passing through Shadows which would otherwise bring you to your destination more quickly. How much does it slow you down? That depends on where you're coming from, where you're going, and how many variables you're trying to control.
Again, it's important to remember that sometimes reaching your destination requires passing through certain Shadows, or Shadows with certain characteristics. I'll let you delete these things, if you stop worrying about the destination when you do so. There will be occasions where you cannot both delete a certain object and move towards your destination -- these should be somewhat obvious when I'm describing it.
Hellriding is how to get somewhere in a hurry. You care little or not at all on actually controlling what Shadows you pass through, your sole focus in on the destination. You cannot Hellride without a destination in mind.
Note that taking the Royal Way is basically a leisurely stroll through Shadow. Normal Shadow-walking is like jogging through Shadow, or perhaps taking a brisk walk -- going the quick way, rather than the scenic route, let's say.
Hellriding is basically Pattern-sprinting. Think of somewhere you might walk to. Now imagine going there full-out, running. You're not at a Hellride quite yet ... now, instead of following the streets, how about you just run through the walls?
Hellriding is brutal, dangerous and exhausting. If you say "hellride", I'm going to assume this definition of hellride.
I can only think of one example of a Hellride in the books which was followed immediately by exertion ... that's when Benedict chased Corwin. Benedict lost the ensuing fight -- that should give you some idea of how exhausting it is. If you don't have a huge Endurance, you might want to approach your Hellrides with caution, if you expect to encounter danger at their end.
Pattern Imprint is, far and away, the most draining power to use in the game. In the books, Corwin (who the rulebook interprets as having the highest Endurance in the game) rests before doing anything stressful after walking the Pattern, and though expecting to be chased by an angry Benedict, feels the need to take a break and get some sleep after a few hours of Hellriding away from Avalon.
Normal Shadow walking and taking the Royal Way are obviously far less stressful -- probably taking less of a toll than Shapeshifting or Logrus Mastery -- but the more difficult and aggressive Pattern powers are tiring.
If you get too tired and you slip (even with normal Shadow walking), you could be dead. The more difficult the thing you're doing is, the more likely that'll be your fate. If it's clear that you're tired, injured, or otherwise weak, and you decide to push it, be aware that the results can be dire -- particularly if you have bad stuff.
That's it ... any questions?