Urinal Ettiquette

A question for the dudes.

Suppose you encounter the following urinal configuration:

u U U

On the left is a kiddy urinal, followed by two adequately divided adult urinals. If you enter the restroom and someone is using the rightmost urinal, is it acceptable to use the middle one? In other words, does my preference for a non-kiddy size urinal override the traditional buffer requirement?

If you believe that it is acceptable to choose to override the buffer, is it then preferable when approaching the above configuration as a first arrival to use the right most urinal, or to relieve a potential newcomer of an unpleasant choice by using the middle urinal, thereby making the right one the only viable option?