I work a 4/3 average alternating between earlies and lates, we always get at least two days between an early and a late, sometimes four, unless we choose to do overtime. Even so, the first early is an absolute killer for most due to the difficulties of getting to sleep when going to bed earlier.
How on earth is combining earlies and lates in the same week with no rest days even remotely safe? ASLEF at my place would never allow it, why do BALPA?