Generalized case plurals

“I had a phone conversation with ten dentists” in English is a conference call, but in Dutch it would usually mean ten separate calls, one with each. Whereas “I had conversations with ten dentists” when put into Dutch would tend to mean several successive calls to each.

It’s not always very clear-cut, admittedly. But the logic in natural English seems to be that if there are multiple objects – say a football team’s shirts – the plural remains in the generalized case of a player putting a shirt on=> the players put their shirts on. The players (as a group) put all the shirts (plural) on. Sure, it was one shirt each, but saying the players put their shirt on sounds wrong. That example with the dentists is from real life, and so are these:

• Geef de naam en kleur van de twee draden in de schemerlamp => names and colours (otherwise the answer would be a single colour plus a single term, applying to both wires)
• all our employees have a medical degree => have medical degrees (the singular would tend to imply they’ve all got an identical degree)
• Which countries had a large empire in the 16th century but had lost it by the 19th? => large empires … had lost them (otherwise you’re talking about a single, shared empire)

If you think your sentence is ambiguous, and want for example to emphasize that each dentist only received one call or that each player only put one shirt on, you can use e.g. each or own to make it clearer. And the singular form is then fine: I had a conversation with each of ten dentists, the players each put their own shirt on.

Prevalence: high. A biggie, in fact. A surprisingly common issue that can genuinely affect the intended meaning.
Frequency: moderate. Turns up in everything from everyday speech to legalese.
Native: yes. There can be inherent ambiguity in the meaning (in both languages) and you can get it wrong if you’re not careful.