Did they just give up on example sentences?

[alo]

@rever4217

Clearly not.

@Leebo

If that changes, it’ll likely happen all at once in an update they announce.

@tls

Any ideas though, what could be a reason if an item above level 20 has more than one context sentence?

Well, for 幾つ at least, they added the two new sentences in a content update:

@camfugu

幾つ - added “how old” to meanings, updated meaning mnemonic, added “how much” to blacklist and added two new context sentences

And from searching the forums, it seems pretty random when they do so. For example, they added a second sentence to 凹む (Level 59) a year ago.