Yes, I agree. My routine is to drain the old stuff out, then refill with Prestone Radiator Flush and distilled water; drive the car around the block a few times to get that stuff well circulated; then drain that stuff out and then put in the new coolant. The last time I did that the second draining in the process came out quite clear, plus with the modern compositions of the coolant these days to inhibit corrosion I figure I'm good for two years. By then the tendonitis in my left forearm from reaching up to get at that engine block drain plug should be healed enough to have another go at it
.