When I had my deferred compensation plan at work (like a 401k, but technically a 457b), I would think of an investment mix I wanted and rebalance every quarter. I wanted some exposure to foreign stocks, so I might put 30% in that. Then I would want something in cash or bonds so I might put 20% in there. The rest would be US stocks, so I would 40% in large cap stocks and 10% in small cap stocks. That was a reasonable diversified portfolio. Then by rebalancing you make sure you stick with that mix, but I also like that if foreign stocks did really well, you would end up selling some of that at a high and distributing it to the others that didn’t perform as well, so it was kind of a way of doing market timing, which I was never able to do successfully otherwise. The fallacy of that was that investing 100% in stocks always seemed to do better over the long run than watering it down with bonds or even foreign stocks, which seem to generally underperform domestic stocks. I never liked bond mutual funds because rather than really getting nice safe fixed income, it seemed like you were actually betting on interest rates, which would fluctuate.
This past year I did a rollover where I put all of my deferred comp funds into a conventional IRA at Vanguard. Both accounts are funded with pre-tax salary and will have taxes when I withdraw the funds, so no taxes were due because of this transaction, but I will still pay taxes later.