I pretty much lack that itch, to be honest, probably mostly because a lot of my conlangs are extremely regular in their morphophonology. The language of mine with the biggest lexicon is Jalvaan, which is very in love with stem (and tone) alterations; that lexicon, however, only has about 200 entries.

Well, maybe the first paragraph was wrong. I lack that itch, but the appeal of irregularity can interest me anyway.

Anyway, dictionary expansion with me is mostly with poetic names and kennings, formal terms, borrowings et cetera. Technical terms matter less because I both do very low-tech conworlding and wouldn't write (many) technical texts either.