Does "Don't put your eggs in one basket" apply to vanguard mutual funds.

I know this subs focus tends to be budget, tackle debt, max tax exempt options followed by low management fee mutual funds.

Well as a 29yr old with virtually 0 debt besides a mortgage (~3.6%), I hammer vanguard funds with my excess cash.

Is investment "diversity" enough with mutual funds?

This sub has a boner for Vangaurd, as do I. But if 100% of your savings outside 401K/IRA is with vanguard, are you at any considerable risk? Should it be more like 90% vanguard with 10% elsewhere? Maybe 70% Vanguard, 20% land purchases, 10% bank CDs.

I'm mostly invested into Vanguard's Total Stock, Total International Stock, and Healthcare funds.

TLDR: Should I really be all in with Vanguard?