Nobody follows such a convention. Nowadays frigates, destroyers, and cruisers are designated as such for political rather than military reasons.
Except arguable China, which has:
1. The Type-55 Large Destroyer
2. The Type-52D Destroyer
3. The Type-54 Frigate
4. The Type-56 Light Frigate
And naming things correctly is not just for military reasons. It's just common sense so people don't get confused.