Is there anything wrong with using Target Date Funds for retirement savings up to a required amount and then investing any excess in riskier vehicles?

Let's say my target retirement number is $5M, and I can get there strictly with my 401K and IRA. Is there anything wrong with using TDFs in the 401K/IRA and then using my brokerage account to invest in riskier assets (e.g. VTSAX without bonds)? Obviously I'll be overweighted in equities for my whole portfolio, but if I'm on track for retirement does it matter?