I can’t speak for Namibia, but growing up and hunting Zim, was taught that 150m was a long shot.
Most hunting in Zim is done in fairly thick bush though, and on lighter calibers getting your shot bounced by a random twig is a real concern. The only anima I have ever wounded and not recovered in my life was an Impala at about 50m out, .223, boiler room shot. It must have tipped a twig that I didn’t see though. There was great blood, but that impala ran and we tracked it for about 3kms before the blood ran out and we never found it. Spent the better part of day looking, still to this day I don’t know where that shot went in to give me that much blood but no animal.
The point of my story is, keep the shot as short as possible to negate any possibility of having your shot tipped off.
Obviously if you’re hunting an area that is more open, then you can get your ranges up.