The 1” rule was one of the rules that caught people out with 8th Edition was first introduced. Either they forgot to do it when they deployed or they didn’t take it into account when they moved and manoeuvred their units. Now it is pretty much second nature to everybody when they deploy and finish their movement but is still sometimes forgotten when moving.
The easiest way that I have thought of to remember it, is that EVERY unit (friend or foe), every building and every piece of impassable ground has a 1” bubble around it that you must not enter unless charging.
Like all GW mechanisms you can always find a grey area. By the letter of the rules every board edge is impassable and therefore a case can be made that you can’t go within 1” of the board each. I haven’t seen this played – and I believe it opens up a can of worms if you try to play a 1” exclusion zone around board edges. [As an aside, remember fleeing units are destroyed as they leave via a board edge triggering potential panic checks on units within 6” of a unit when it hits the edge].
So how do I think the 1” rule has impacted the game? Well I certainly think it has cleaned up a lot of charges now units have to be an inch apart. It’s important to know how it impacts on overruns and pursuits as unless you are going into contact that 1” must be adhered to. Also that spacing makes measuring spaces far more intuitive as you now the minimum distance must be 1”.
This makes charges against multiple units a much less common thing – and where they do occur they seem easier to resolve – again cleaning the game up.
Rule Change: B+
[One thing that causes me to smile is that it is clear that GW has instituted this rule to tidy things up by putting a clear separation between units. However, you’ll still get O&G players insisting their base size is 1 ¼” so that they can position it to hit two units. I'd expect that from Dwarfs but I thought O&G players had more pride! Yep, GW created a new base size just to allow them to circumvent the 1” rule. At least put it on a 40mm and acknowledge you are being gamey buggers]