Worth reading lower band books

[confusedinlondon]

My son was on the Orange/ level 6 book band before covid caused scools to close down. I purchased a number of books off ebay and ensured he reads 4 or 5 times a week. I also ask him questions to check his comprehension. He has now confidentally read at Turquoise / level 7. Would it benefit him to read some of the lower level book bands or shall I get rid of them. I am minded to sell them on eBay but I think it might be worthwhile for him to read at a lower level sometimes.

if he likes to read them, keep them.
at that age repetition is a good thing.
if he finds them boring then get more books his level on different subjects and from different authors.

Unless the only way you can buy new books is by selling the old ones, I would keep the lower level ones if he enjoys them.
Repetition is good. Keep lots of variety of books around and encourage him to pick what he likes and read.

At that level he should soon be reading normal non-scheme picture books so will have loads of options. Are local libraries reopening where you are?
Now some of the branded scheme books my kids wanted to read and reread like normal books, others not. I wouldn't make him reread if he doesn't want to.

If he likes to reread the books, and you have space and don't need the money, I would keep them.
We kept all the books since nursery until end of yr6. We finally got rid of it but it was quite hard to convince my dc to do so, because he liked to reread the books he read in the past. Even the ones he read in nursery. Not all, but some of the books had so much fun memories.