Hi Tom,

To explain further it is actually quite difficult to translate 'one does this for one's ....' as in French 'on' doesn't bear the same register as in English.

If you take a look at the following lesson nearly all the translations use, people, we, universal you and it will rarely translate with 'one'.

https://french.kwiziq.com/revision/grammar/on-can-mean-we-one-and-people

In some cases, you might use 'nos' or 'ses' depending on what you are trying to say -

On a tous nos petits secrets = We all have our little secrets 

On a tous ses petits secrets = Everyone has their little secrets (more general comment) 

For instance to translate something like:

One must try to remember to bring one's ticket 

You would have to say 

On doit essayer de se rappeler d'apporter son ticket 

or

il faut essayer de se rappeler d'apporter son ticket 

but it doesn't convey the precious register you want to create.

If you added :

Puis-je vous rappeler qu'on doit essayer de se rappeler d'apporter son ticket

that could translate as -

'May I remind you that one ......one's ticket '

A few more examples -

On aime voir nos amis régulièrement = We like to see our friends regularly

but 

On aime que ses amis soient heureux = We love our friends to be happy

(generality) 

On ne doit pas dire du mal de ses amis = One mustn't speak ill of one's friends

(rare example when I probably would use 'one' and 'one's )

On ne doit pas dire du mal de nos amis = We must not say bad things about our friends.

When I said that 'ses' didn't make sense in the 'rien de tel qu'un bon repas après tous ces efforts' from 'un repas Savoyard', it was because the only personal pronoun was 'nous' and that 'ses' wouldn't make sense in that context.

I hope it is clearer now...