You don't have to. Just remember to balance it out later with something on the lower end of the qualities.
Personally, I use a die roll to help me decide if Clusius got his hands on a good or an inferior quality book. If my luck turns out to be consistently rotten, I may decide to arbitrarily add someting near the end of his period.
If you check out my topic, you'll see that my magus isn't very focused, nor is he making optimal decisions all the time. Only 67 xp and 20 levels of spells over 8 seasons. I'm just letting the story carry me.