If you want to look at total minutes, Tatum is 12th in the league at 1,973 total minutes. Right in there with SGA, Edwards, Jokic, and Brunson. Per game, he is 10th at 35.9 min/gm. I am not concerned at this point.
The season we were in the finals vs. GSW, Tatum had played in the summer with the Olympic team. I think that was a bigger issue than the number of minutes through the season, although both can be an issue. They will probably rest him some towards the end of the season, the last 5-10 games or so.
We have tiers of players when you consider minutes. Tatum, Brown, Holiday, and White are all 1,750 to 1,972 min. The next tier is Porzingis, Horford, Hauser, and Pritchard all at about 1,200 minutes. Then it drops significantly for the rest of the players.