Time is the only thing everyone spends at the exact same rate. What you get for it is the difference.

Money, talent and luck arrive unevenly. Hours do not. Everybody at your school gets the same allowance of them, and the variation between people shows up entirely in the exchange rate: what the hours were traded for, and whether anything is left over afterwards. It is oddly level ground and oddly unforgiving.

Look at one block of your week, say the three hours after dinner, and ask what you are currently getting for it. Keep the trade if it is a good one. If it is not, change the use of that block alone and leave the rest of the week where it is.