I think you are asking if the modification is necessary to allow a full mag + 1 in the chamber ?

If so, then that is correct. The extractor must be modified and you must hold down the top round in the mag to allow the bolt to slide over and chamber the loose round.

I do not do that, my rifles are not so modified. If it is a four round mag , then I cycle the bolt when making ready and have 3+1 in the chamber.

I think it is very much personal preference. I like to be able to make the gun safe for whatever reason ( entering vehicles, climbing fences taking a piss etc etc) by pulling back the bolt, thumbing down the round and closing on an empty chamber. If I had to think about a loose round then it would play on my mind both ways, ie is the gun clear when I need it to be, and conversley is it loaded with that extra round when something pops its head up.

500

I am not suggesting that the modification makes the Mauser extractor really week or that it is prone to failure. However by definition as it involves the removal of metal it must weaken the tip to a greater or lessor extent.
IMHO the chance of needing a 5th round is a lessor risk than having a modified extractor jump the rim. To make the mod work, sufficient metal must be removed to allow the extractor to jump the rim on the forward stroke before the outside face of the extractor hits the inside of the RHS bolt raceway. If an un-modified extractor is fitted carefully, there is insufficient clearence here to allow the extractor to slip over the rim on loading and hence on extraction.
IE it cannot run over the rim on sticky extraction, the very worst it can do is rip the rim off.

Regards