If you don't, every time you see video of a fast jet snotting up a valley, you'll look out of your office window and think to yourself,"I wonder if..".
First of all that is a superb piece of advice.......
Secondly groundschool........ Post IOT all pilots spend six weeks at Cranwell doing Common Core Groundschool (CCG). This is an intensive 9-5 course covering met, principles of flight, airmanship, navigation etc. Then for every aircraft you fly after the Tutor more grounschool will follow. Think Tucano, Hawk and METS groundschools all last a month.
You show me a pilot who likes groundschool and i'll show you a loser. That said, it is a neccessary evil. Stick with it....