I'm not as up on the French, but I wouldn't be surprised to see them working more like the South Africans given their prop depth, and levelling out the minutes. I don't think it's too relevant for us though, without bigger squads (and more importantly more money to fill them) we can't expect to operate that way. Even if we did it's still not an argument for bulk spending on the top tight head, you want a more even distribution of salary between the group as whole, somewhat in line with the way you'll distribute minutes.
On the other hand, players like Sinckler, Ala'alatoa, Lomax and Furlong (more for country then club, against the norm) have regularly averaged above 50 and approaching 60 a season, with the standard for them to be going beyond 50 minutes per game. It's definitely not every season, but it's pretty clear that their teams are targeting over 50 minutes from their prime tight head as standard.