I agree, "wholly enough" is nonsense in normal language - it's sarcastic and extremely literary. "quite enough" or even "really enough" would be good.
Any difference between "dvacet roků" and "dvacet let"? I can find the word corresponding to "let" in Polish and Slovak, meaning "summer, year" but not in Czech. Is it a borrowed idiom?
I believe it's derived from léto = 'summer.'
When counting years, you usually use rok with 1-4 and let with 5+.