I would love to do a little bit of studying.
Test 1: Tell the French at Crecy to ditch the crossbows for longbows, and show them about the effective ranges.
Test 2: At the Battle of Chang Ban, tell Cao Cao that Zhang Fei is just bluffing on that bridge, and that there is no army past it.
Test 3: Tell Sun Jian to recruit a few more officers before attacking Liu Baoi.
(More officers=Sun Jian leading army from safety, and not getting killed in an ambush by having a boulder land on him.)
Test 4: Give some penicillan to Alexander The Great
Test 5: Convince Attila The Hun to behead the Pope instead of listening to him, and falling back from his conquest of Rome.
Test 6: Try to stop Roger Waters from leaving Pink Floyd for a solo career.
Go back and tell myself not to do any of these things after gathering results.