I found that using the historically accurate 1 tracer per 5 rounds to be very effective method during testing. I wonder why HTC don't have this option because every round emitting a tracer can make the front view very busy in terms of particle effects.
I've always felt more comfortable with the tracers turned on. I always use the gun sight for the initial vector interception calculations of the target. All though I would use the tracers to make adjustments. My normal fire routine would be as follows:
Aim, quick squirt, check tracers, repeat.