I tend to do my big compound movements explosively on the concentric and controlled on the eccentric. I don't really think about the rep cadence at all, just make sure that I am getting full ROM and a controlled negative.
Isolation work is a different story though, there I do focus on tension throughout the entire movement and a peak contraction. Only exception to this I can think of would be hamstring curl variations, when I do a controlled concentric I don't feel like my hamstrings get much of a workout, the weight also has to get reduced by quite a bit. So for these I stick to the full ROM, explosive concentric and very controlled eccentric.
yes i like to make the most out of my training too..why waste your time when you train? If you train 40 mins then make sure you do your best. you are one of the more knowledgable guys on here and good to read your comments. Be a thinking trainer !!