So the article I'll link at the bottom states minutes and seconds weren't really used until around the sixteenth century.
How did people, especially scientists, time things before this? If a scientist was performing an experiment which involved timing, would he use a bunch of hour glasses, count it out, just perform every part of his experiment at the same time and note which came first?
How did people say they'd be back in fifteen minutes? Did they just use vague terms like "soon"?
http://www.livescience.com/44964-why-60-minutes-in-an-hour.html
Well there wasn't a lot of formal (much less precision) "science" prior to the 16th century (the 1500s). The most precise science of that period was astronomy, and astronomy is the means by which you measure the time in a pre-clock age (as the article notes, the "minutes" and "seconds" of a clock are derived from angle measurements — you can, for example, watch the rate that a given start crosses a given point, and from that calculate the speed of the rotation of the Earth).
What we think of as "science" shows up around the late-16th through 17th century, and it is non-coincidentally related to the drive for precision that gives us the instruments and concepts of modern timekeeping, among other things. The drive to quantify and improve precision is arguably what the "scientific revolution," inasmuch as we want to claim that there was such a thing, was about.
For non-scientific work that needed a reasonable degree of precision (cooking, for example), it was a combination of things. Firstly, developing the right sense of timing without any absolute external guide took practice. Instead of "poach the fish for five minutes", it would be "poach the fish until the flesh is white" or "until the water comes to a boil" or "until the liquid is reduced x amount". Gradually, you'd just figure out about how long it takes to poach the fish without really having to watch for any of the other landmarks.
If you read pre-modern recipes (and really up until the "Home Economics" movement of the turn of the last century which was a scientific approach to domestic tasks), most of them don't mention precise measurements like time to the minute, or exact amounts (it's always "a teacup of flour" or "milk to cover the potatoes" or even just leaving it up to the cook's judgment).
Likewise, with work. You didn't show up for work at 9:00 AM, you showed up at dawn, or "after the morning meal", whenever that happened to be. In general, before the Industrial Revolution, people just weren't bothered about time in the clock sense. Shops opened when they opened. Events happened "after church" or "at sundown". Nobody said they'd be back in ten minutes, they said they'd be back "in a little while." Also, since most people worked for themselves or shared work as a household, there just wasn't a whole lot of scheduling to be done, and a small shift in time didn't matter very much.