In my opinion, it's not serious for 2 injuries in 2 days. In previous season, One of my teams used to suffer about 15 injuries in 1 week and the total period is about 50-60 days. I just checked my L11 team. In past week, it also has 8 injuries for total 33 days.

But I also notice the terms of injuries is becoming longer and longer. In this season, most terms of the injuries are over 5 days. To me, any injury with terms >= 5 days is similar because all of them can be healed with 15 red packs.

Usually, I don't hesitate to heal long term injured players. If the player is low quality, in bad form, or soon out of contract, I may consider to sell him. If red pack balance is close to zero, I may tolerate some players to recover in 5 days. For injuries less than 5 days, I am very cautious to decide whether I will heal them with red packs.