Matthew Poole and continuators on 1 Kings 9:23

23 These were the chief of the officers that were over Solomons work, five hundred and fifty , which bare rule over the people that wrought in the work.

Obj. They were onely 250 in 2 Chron. 8. 10. Ans. First, Those might be Officers of another sort; for they are not said to be over the work, as these are, but onely over the people. Secondly, The 250 were Israelites, who are therefore distinctly mentioned in that Book, where many things are more exactly noted than in the former; and the other 300 were strangers, who therefore are neglected in that more accurate account. Or, Thirdly, There was but 250 at one time, which is noted there, and 250 at another time, (for it is apparent they did their work by turns) and the other 50 either were Superior to all the rest; or rather, were a reserve to supply the place of any of the 500 when there was occasion, which might frequently happen. And so this was an act not unbecoming Solomon's Wisdom, to make provision for Emergencies.