Though Cristiano Ronaldo is a type of player who does not want to miss any match if he can play, he and his coach must be realistic that he is already 38-years old. To avoid injuries and more important serious injuries that can destroy his career suddenly as well as to help him have better contributions for Al Nassr in a long season, he must know when to take a rest and his coach can help him to take rest in unimportant matches.
At this age, being able to play at highest level like he is doing is already very barely seen but he needs more careful and good plan to diversify his energy through a season. Al Nassr has many attacking star players and they can give Cristiano time to rest and recharge energy.
Since the year of 2001 when Cristiano Ronaldo started his official appearance in hid football career, he has appeared in 1,229 official matches and have scored a total of 881 goals making him the 4th player in the ranking of most appearances in the football history and highest goal scorer in the same ranking. That's a lot of history to break and it is only a testament of his unrelenting efforts and capacity to play matches.
For the sake of history, Cristiano Ronaldo is the most performing striker in the history of football going by this ranking especially as we factor in his longevity to play so many matches in the span of 22 years approximately. I think Ronaldo is still looking at breaking the record of becoming the player with the highest appearance as he has an additional 182 matches to play to take over the ranking ahead of Peter Shilton, an England goalkeeper who kept the record since 1997.
In my calculations, right me if I'm wrong, Ronaldo needs approximately 6 more league seasons to play to lead the ranking of the most appearance in the football history. I don't think this is necessary as he's already the highest forward with such great achievement.
Like you have mentioned, it's better if Ronaldo takes good rest off some unimportant match while he allows other young upcoming star players to shine too. Else he could end up with an injury as it only normal to think of that if he continues to play every match. If Ronaldo goes into retirement because of an injury, it will be a greedy thing to deal with.