Number one reason why people don’t catch fish is lazyness. Keep drilling often I drill 50-100 holes before I really start catching them. Different lakes have different structures. But 30 seconds to a minunte a hole is plenty unless u mark them, even so if they aren’t aggressive don’t waste your time.
On a lake I never fished, I’ll check over the lake map, use my basic fishing knowledge that I use to find the species of fish I plan on targeting. Go there, pop a few holes. Drop the vexilar down. Fish for 5-10 minutes. If not at least marking something. On I go to pop more holes until I find a place to fish for hopefully the remainder of my fishing day. Good luck & have fun.