As it should be. A 50 metre penalty is meant to be a big advantage for the attacking team, much more compared to a standard free kick, and if the attacking team thinks the optimum time to make use of the advantage is 25 metres down the oval, then by all means.
It was too much. 25 to 30 metres is what it always should have been from around mid 1980's. for some dumb reason they went from 15 metres to 50 sometime after 1987. Jimmy Stynes famously gives 15 metres away in 1987 prelim final
The worst part about 50 metre penalties is that they exist at all. Should be 25m. Seriously some of the trivial garbage that leads to massive advantages for teams is just a load of crap. Stuff like not giving the ball back properly, following your man through the protected zone but going around the player the wrong way etc etc. Its all so trivial and not in the spirit of the game to give massive penalties for minor mistakes.
50m penalties should be reserved for violent hits that come late and other violent acts.