Ok, I grew up just driving on old fashioned mt's.
And from my hoop-D civic 4cyl to my V8 Dakota all the way down to my 350R 4Stroke the shift range has always been the same general idea.

1st off over looking at the RPMs I was always taught to simply listen/feel the engine and shift when it tells you "Im going as fast as I can while maintaining acceleration"
For Me this point usually falls into the 3.7-4000 range ideal being "getting the most out of each gear without making your engine have to compensate or work harder"

My 2004 Infiniti G35 Sedan Like mannnny other posts has this Short shifty lag to it. I dont understand being in 5th gear by 50 mph, in order to go any higher than 75 mph feels like its killing my car, yet there is still 5K rpms "available' before red zone. Is it safe to say just ignore the sound like my engine is going to take off like a rocket out of my hood shift at a higher rate like 5-5.7K rpms??? or is short shifting just where its at and the extra 80mph my speedo says it can go just stay virgin? lol

 

Your car has a redline number on the tach for a reason. Drive it anyway you want as long as you stay under redline. The motors are designed to operate well in the higher RPMs, they're just not very quiet in doing so.

 

You can reach 6krpm with half throttle but the timing advance will be considerably less than WOT. I've found the G is most responsive in gears 2-5 when you mash WOT but still shift at 3.5k rpm. Doing the opposite, 50% throttle and shifting later in the RPM's makes the engine feel loud and gutless.

Basically if I'm accelerating at all the pedal is WOT, I almost never make small adjustments unless the roads are wet.