When flying RC, there is always a Risk. The Wind, the Sky, the Light Level, the Terrain. Each time I fly I assess the Risk and make the decision to Fly or Not.

I Range Check my Radio, I check the Battery Voltage, I check for Airframe Weakness, and I check Control Linkages.

I try to prevent Crashes that were caused by something I had control over.

Unless you have really Cheap aircraft, I would not Risk using Cheap batteries. Should you Hit someone or Damage their property, I don't think they would appreciate you Skimping on the Batteries.

I suppose if you keep a close eye on the Battery Voltage, you can make the decision whether to Fly or Not, but even with Good Batteries, you can lose a cell, In Flight, even if the Battery Voltage, at Takeoff, was in the acceptable range.

Why take the chance for a few bucks?