I should qualify my Luddite-looking remark above by stating clearly that that's what works for me, and perhaps me alone. In a former life as a roadie I was obsessed with gadgets and data, and at that time that meant a cycle computer and a heart rate monitor (I'm old). When I started up again on the track, I found the data depressing as a beginner (too slow), so I ditched the gadgets. From my perspective, this made it easier to focus on properly bringing maximum intensity and my best form to the efforts. Basically (and some may jump on me for saying this), I go by 'feel', and I for me the lack of numbers and flashing lights makes it easier to focus on just how I feel. Also, at the track I can gauge myself against my training partners.
Bottom line, this is not an exact science, and I do it for fun. And data is not fun for me. Carleton is a different sort...