How many atoms can be reduced in a single redox reaction?
I'm not sure if I understand your question correctly, but consider the reaction

$$\ce{CH3-SH + 3 O2 -&gt; SO2 + CO2 + 2 H2O}$$

where methanethiol is oxidized with oxygen to sulfur dioxide, carbon dioxide, and water.

Thereby the oxidation states of sulfur and carbon change from $-2$ to $+4$ and the oxidation state of oxygen from $\pm0$ to $-2$. So sulfur and carbon atoms are both oxidized while oxygen is reduced.

I hope this answers your question.