How do you allow players to explore your fog-of-war dungeon, maps, etc.?

Hi! The question is framed for a discussion more about any special rules you might employ with map exploration in roll20, rather than actual technical implementation. I realize the thread title could be misleading, so I wanted to clarify that right away--apologies! I was wondering if any of you have lovely tips or advice on how you allow your players to delve through your fog-of-war dungeons or maps? There is an easy implementation of a "soft rule" in requesting that your players move tokens slowly or square-by-square to allow gamemaster exposition and reaction, but something about it being a "soft rule" seems... fluffy. One of the main issues I'm trying to solve is that, sometimes (especially in a pick-up group for a one-shot) a player will drag their token with rapid and distant movements even given the "soft rule." At the same time, asking that players each take turns moving in set increments of X squares or X feet to keep everyone relatively together almost like in an initiative order seems potentially cumbersome. But perhaps I am wrong! There is also the possibility that the grid may be better used to strictly draw and measure out combat scenarios. Should dungeon exploration thus be left mainly to narrative exposition instead? I'd love to hear everyone's thoughts, opinions, and experiences on the matter.

I personally have the party establish a turn/marching order and let them move their tokens on their turn according to their movement speed.  I often have the party roll for initiative outside of encounters.  Adds to the suspense of dynamic lighting and keeps the party on their toes. Once it's evident there isn't an immediate combat, we move back to a turn order based exploration/movement mode. I would also recommend using "update on drop" to prevent someone from taking their token and using it like a flashlight all over the map to reveal.  Forcing a turn order movement can be time consuming and sometimes we hand-waive some of the transition between events with a little narrative to help speed things up. Our particular group would quickly tire of just jumping from one event to another, to another, however...  It's nice to slow things down a little.  Remember that movement isn't the only thing that has to happen between encounters/events.

Not sure if this answer counts as "technical" or "a rule" but, on the start of the 1st session, when I assign Tokens to Player-Characters, I ask all the Players to select their token, and move it with the Arrow keys (so that they move 1 square at a time). If you can get them controlling the token with arrow keys, as long as they don't click super-fast, you will be able to see their steps and it won't appear to jump far across the room as it can-do with a mouse click-and-drag-and-drop motion. So, my rules-tip is "Everyone use the arrow keys to move your token, not drag-and-drop".

How do you do diagonals with arrow keys, though? :)

Doesn't pressing both arrows at same time still go diagonally (ie: up+left) ?

Yes it does. I was surprised to learn that a while back. I had been just trying to press them in rapid succession.

If you can set your Grid Size (not Units) to .5 or .25 or .2 or .1, then you can allow extremely very-much more discrete (accurate, choosable) token placement positions. I recommend .5 at first when trying this technique. With the more sub-divided grid, even if the "both arrows at the same time" doesn't always work for diagonal, doing an up-and-over (2 clicks) should approximate it nicely.  The difference on a "1" sized grid is a longer (distance-wise) swing out-of-your-intended walking path if you go, like chess, over and up. A fractional grid size really helps with, effectively, antialiasing the diagonal.