You should definately have a stop loss in place to manage your risk. For a time frame of 5 to 10 years I would be looking at a trailing stop loss of 20% to 25% off the recent high.
Another type of stop you could use is a volatility stop. Here the more volatile the stock the larger the stop whilst the less volatile the stock the smaller the stop. You could use 3 or 4 x Weekly ATR (Average True Range) to achieve this.
The reason you should always use a stop loss is because of what can happen and what did happen in 2008. Some stock markets have yet to fully recover from their peaks at the end of 2007, almost 9 years later. What would you do if you were planning to hold your positions for 5 years and then withdrawal your funds at the end of June 2021 for a particular purpose, and suddenly in February 2021 the market starts to fall. By the time June comes the market has fallen by over 50%, and you don't have enough funds available for the purpose you planned for.
Instead if you were using a trailing stop loss you would manage to keep at least 75% of the peak of your portfolio. You could even spend 10 minutes each week to monitor your portfolio for warning signs that a downtrend may be around the corner and adjust your trailing stop to maybe 10% in these situations, protecting 90% of the peak of your portfolio. If the downtrend does not eventuate you can adjust your trailing back to a higher percentage.
If you do get stopped out and shortly after the market recovers, then you can always buy back in or look for other stocks and ETFs to replace them. Sure you might lose a bit of profits if this happens, but it should always be part of your investment plan and risk management how you will handle these situation.
If you are not using stop losses, risk management and money management you are essentially gambling. If you say I am going to buy these stocks and ETFs hold them for 10 years and then sell them, then you are just hoping to make gains - which is essentially gambling.