Normal Procedures
Checklist philosophy
Normal procedures are about repeatability. Flows accomplish the action; the checklist verifies it. The trap in questions is the pilot who 'knows the airplane' and recites a checklist from memory during a high-workload phase - the purpose of a written checklist is to catch exactly the item you forgot. Use the checklist at the phase of flight it was designed for, and treat any interruption (a diversion, a frequency change, a passenger question) as a signal to restart the checklist from the top.
Cruise, fuel management, and systems
In cruise, the recurring tasks are fuel state and balance, pressurization and cabin altitude, anti-ice/deice as conditions require, and monitoring of engine and system parameters. Fuel management includes crossfeeding and tank switching per the AFM; running a tank dry, or exceeding lateral imbalance limits, is the classic wrong answer. Anti-ice has a cost - engine bleed and wing anti-ice reduce performance and increase fuel burn; turn it on before entering visible moisture in freezing temperatures, not after.
Deviations and judgment
Weather deviation, altitude changes, and route changes all require a clearance in controlled airspace; the PIC retains emergency authority but should advise ATC promptly. Logging and recordkeeping are part of normal operations, not an afterthought.
Worked example: At 12,000 ft cruise with 900 lb usable fuel and a burn of 60 lb per hour per engine on a twin, endurance is 900/120 = 7.5 hours; applying a 45-minute IFR reserve (90 lb) leaves 6.75 hours of usable cruise time.
Rule of thumb: any interruption during a checklist = start the checklist over.