Ad hoc and As the need arises

Ad hoc adverb - For one specific case.

As the need arises and ad hoc are semantically related. in for present purposes topic. In some cases you can use "As the need arises" instead an adverb phrase "Ad hoc".

Ad hoc and as the need arises are semantically related. Sometimes you can replace phrase "Ad hoc" with "As the need arises", this phrases are similar.