In another question on this site, there is some discussion on the view that the so-called "strong verb" class in English is no longer "productive" - that is, newly formed or coined words (neologisms) are never (or at least are not properly supposed to be) assigned to this class. For example, most speakers would not make the past tense of "I gerrymander" as "I gerrymoonder" - they would say "I gerrymandered". Since English has only two verb classes (strong and weak), this makes it easy to assign a verb class to a new word.
I've noticed that neologisms or loanwords in Spanish tend to belong to the ar verb class in Spanish, for example, hackear and emailear, although there are two additional primary verb classes, er and ir. I can't recall anyone ever saying "prohibido spamir", "el presidente ha gerrymanderido los distritos", or similar.
Is it standard in Indo-European languages for there to be only one productive verb class for neologisms? If not, are there rules for how to determine to which verb class a newly coined term should belong?
I have some experience with Hebrew (an Afro-Asiatic language with seven verb classes), in which the verb classes themselves ("binyanim") are vaguely associated with specific types of voice (for example, reflexive, passive, intensive, etc.) (there are exceptions), and so neologisms are sometimes intentionally placed in the binyan that corresponds most closely to the intended meaning. I've never seen this sort of behavior, though, with an Indo-European language, in which the verb classes have always appeared to lack underlying meanings.