just rev it all the way till almost 8K, then shift up before the rev cut. u will get a very consistent acceleration as next gear will high in rpm.
if u dunwan to heat up the engine so much, just change at 7k rpm.
both way is okay for as long your engine is healthy, and gear oil is still good. get those high grade gear oil such as torco or motul. it's expensive no doubt, but it's worth it. i hardly hear of 20v picah gearbox