If you ask me, it's more about use about 10% of monthly salary to DCA, then save the rest. Because if we are lucky, and a golden opportunity comes again - it might be a good time to be irresponsible and use up to 90% of your savings to buy the DIP.
Using 10% of monthly salary by salary earners is not a bad idea, I consider this one of the best approach when it comes to DCA, cause one would still have reserve funds as a leverage to take advantage of the market when their's a massive dip for instance about weeks ago when Bitcoin fell below $50k. This is the more reason why it's advised that people shouldn't loan money to go into Cryptocurrency, imagine if someone made entry with a loaned money at $60k plus and the market declined below $50k they'll end up being in a big mess cause I wonder how they'll pay off the debt, investing on Bitcoin especially when someone is using the DCA method is meant for those who got a stable income and not some jobless person trying to alleviate themselves with the little funds they got through Bitcoin.
I don't think there is any point deciding what percentage of salary others should invest in Bitcoin because that depends on a lot of factors which varies from individual to individuals. In other words, the percentage an individual should invest in Bitcoin is something the individual should work out by himself to know what will be suitable base on his level income and responsibility because the bigger picture is to invest in Bitcoin and be able to manage the investment properly so they are not sold off when there are challenges. Therefore, one of the key role of the investor is to ensure plans and provisions are made to take care of anything that might make the investment to be sold off.