Counting time period, is ridiculous. It fosters and encourages a host of unchristian attitudes.
~ The attitude of making time instead of making disciples (this attitude seen especially in pioneers).
~ The attitude of quantifying and comparing the sacrifice and spirituality of individuals based on the number of hours they do. This contradicts the principle Jesus taught by the story of the widow's mite. Jesus' showed that it is the subjective personal effort that one puts into their acts of devotion that counts, and not objective measurable quantities.
~ The attitude of comparing oneself to others. Because time can easily be measured it becomes very easy to measure your time against another persons or against the pioneer time threshhold. This contradicts the scripture that says not to compare yourself with others but with yourself.
~ The attitude of objectifying the persons they preach to. Because spirituality, social standing and fitness to move up the theocorporate ladder are all determined in large part by average monthly output of preaching hours, many JWs treat the preaching work as a business to be profited from where making cash equals making hours. In this mindset, the people they preach to are treated as resources to be exploited for personal gain. Ever wonder why JWs call the person they're studying with, a bible study instead of a bible student? It's because they see the person as a bible study that they get to record on their field service slip. They treat people as 'study objects' and 'preaching hours objects', just as some selfish perverts treat women as sex objects.
One time I was riding home from a meeting with a group of JWs and they were discussing how best they can pair up to do their various return visits and bible studies. One practically optimal scenario involved 3 of them going on a bible study. As soon as the thought came up it was quickly dismissed with disappointment because "oh but we wouldn't be able to count the time".