I was talking about "ordinary" transistors that are spec'd to saturate when the base current is 1/10th the collector current.
I know the "typical" curves are much better than the printed max saturation voltage loss but we cannot buy typical transistors.
American transistors (2N3904, 2N4401) are spec'd with 1/10th. European transistors (BC548) are spec'd with 1/20th. I have never seen a 1/50th or 1/100th spec for the max saturation voltage loss of a normal transistor. Maybe you mean a darlington pair of transistors?
The 2N5089 has about the highest hFE that I have seen, 400 to 1200. But its saturation voltage loss is spec'd at 1/10th when some of them are barely saturated (a max of 0.5V).
No, I was referring to single bjt devices. I design a lot of SMPS & dc motor drives using bjt parts spec'd as "low Vcesat". Please refer to attached data sheet NSS12500. It is a 12V-5A pnp device. At 0-3A of current, Vcesat is spec'd at Ib as 1/100th of Ic. But from 4-5A, Ib is 1/10th of Ic.
If you visit On Semi, & just do a general search under "low Vcesat" bjt devices, you will find more like this one. Obviously, as I stated, there are many applications where 1/10 is necessary, & less base drive would be too risky. But lower voltage bjt devices are often employed for FET/IGBT gate drives. They offer high beta at high current levels. Even w/ a base drive of 1/100, Vcesat remains low, even at 3A of Ic.
Of course when Ic reaches high values approaching device spec'd max, beta droop occurs. Then more base drive is needed to assure saturation. At 1.0A of Ic, the 1/100 value is fine, but at the full 5.0A, 1/10 is recommended. It's easy to understand why.
Anyway, that is all I was getting at. If the 1/10 value is needed, then of course I would never risk desaturation by reducing the base drive. But many high gain low saturation devices fully saturate with much less base drive. If the data sheet says 1/25, 1/40. or even 1/100 assure saturation, why waste power by using 1/10? If Ic = 2.0A, wouldn't you rather use 0.020A base drive, instead of 0.200A? Then again, at 5.0A, I would go w/ the 1/10 value.
If the vendor says 1/10, no less, I don't argue. But that 1/10 value is not universal. I'm sorry if I came across as hostile.