Part 1: Being an accurate measurer does not mean carefully moving each of your 150 orks across the table one by one, carefully measuring out 2" between them. With dudes movement, try to be accurate but move quickly. Don't measure every guy - and if necessary ask your opponent if they want you to measure each move or if they want you to eyeball it. If you have that many dudes, your opponent is going to give you the benefit of the doubt.
Part 2: With your large models, monsters, and vehicles you must be very careful with movement. Measure from one point on the model your desired distance, and mark the spot either with a finger, dice or etc. Then move your model to the spot. In my mind it is poor form to measure the distance, pull the tape back in and then move 'roughly' to the spot you were just at.
Another thing you must take into account is the phenomenon of parallax. If you are moving your land raider and you measure from the top of the hull out 12", keeping the tape measure well off the board in height, the distance you have measured will look different to you on your side of the table than it will to me on the opposite side. This happens because you are holding the tape measure even with the top of the vehicle 4" off the ground. Both of us are looking slightly down on the tape measure, at very differenty angles, so from your side you see 12" as being a little farther than it really is, and I see it as being shorter than it is. The result: You get comped badly for movement. The solution: Measure from your vehicles and monsters from their bases or the very bottom of the model - keep that tape measure next to the ground eliminating the strange angles!
Below is an example of what I am talking about. The red dot would represent the end of the tape measure. The higher the dot is offthe table, the greater the angles created and the greater the discrepancy in what we see! Parallax!
