Timing interruptions to production is another aspect that needs consideration. often Mackenzie Paper Division chooses to incur certain costs because the cost of shutting operations down to carry out a repair is judged to be too high. In other words, the high fixed costs of production mean that operations cannot always be bypassed or turned off " instantaneously" in order to carry out changes or repairs. For "big" jobs the turn around time to engineer, fabricate, order and install new equipment can be many months.A decision on "downtime" is never easy. it is typically delayed as long as
possible until sufficient accumulated work exists so that its justification is beyond question.