Stocks are Risky; Pre-retirees and Retirees Must Consider your Time Horizon

The large drops in the stock market over past few days related to the coronavirus epidemic should be a wake up call to investors. Let's review some basic principles of investing.
Remember that your time horizon for retirement investing is the rest of your life and you may live to be 95 or 100!
Selling stocks when the market drops locks in permanent losses.
Stocks often rise and fall dramatically in very brief spurts in reaction to global events. Stock markets do NOT rise and fall in nice steady steps. Dramatic drops and increases are the norm. NO ONE can predict when these dramatic ups and downs will occur!
Stocks are investments for the long run. No money that you will need in the next five years should be invested in stocks. Funds needed in the short run should be set aside in safe places like savings, CDs, money market funds, I-bonds, T-bills, and corporate bonds.
The Bucket Approach to investing takes into consideration the time-related needs of investors. Money needed in the next 1-3 years (depending on your risk tolerance) should be in safe places that will not lose nominal value. Funds expected to be needed in 3-5 years can be invested conservatively in dividend paying stocks, high quality bonds, and other conservative investments.
Funds for the long run (over 5 years) should be invested for growth in the stock market.

This strategy is specific to the retirement decision for pre-retirees (within 5 years) and persons in retirement.

SO:
Investors in the accumulation phase and more than 5 years from retirement should review their asset allocation and rebalance yearly.
Investors nearing retirement should institute a bucket approach for their investments, even if they also have a pension.
Investors in retirement: the recent market plunge should be a wake-up call to carefully review your retirement income plan. DON'T PANIC! If you sell your stocks today your are locking in permanent losses. We went through this with the global financial meltdown in 2008-09. Have investors learned from that experience?

Benefits of a bucket approach:
Predictability and peace of mind.
You can tap assets and still generate portfolio growth. 
Considerations: 
You need to be disciplined about generating a set return sufficient to meet your retirement needs. 

Read all 3 articles below for slightly different perspectives on time horizons for the 3 buckets. 

See: How to Use the Bucket Approach to Make Your Retirement Savings Last by pete Woodring

https://www.kiplinger.com/article/retirement/T037-C032-S014-bucket-approach-make-your-retirement-savings-last.html
"The bucket approach is an effective way to mitigate sequence and longevity risk. The general idea is to set up three or more distribution “buckets,” with different asset classes and different time horizons for liquidation. Note that the time horizon for the 3 buckets will differ depending on the author. This article takes a very conservative approach by allocating stocks to time horizons of 10 years of more. 

The Pros and Cons of a Bucket Savings Strategy by Rebecca Lake https://money.usnews.com/investing/investing-101/articles/2017-11-10/the-pros-and-cons-of-a-bucket-savings-strategy Retirement investors should have "now," "soon" and "later" buckets.  "The bucket strategy can insulate your retirement portfolio from sequence risk and longevity risk. The former refers to the risk of earning lower or negative returns early on when withdrawing retirement assets. The latter simply means outliving your savings."

What Is The "Bucket" Approach Strategy To Retirement Income Planning? by Jamie Hopkins https://www.forbes.com/sites/jamiehopkins/2019/04/25/what-is-the-bucket-approach-strategy-to-retirement-income-planning/#7b09608539d6