An equal number of {HEAD ~ additional write operations} compensates for the additional reads at {TAIL ~ a later point} 
An equal number of { HEAD ~ additional write operations } compensates for the additional reads at { TAIL ~ a later point }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL