Is dollar-cost averaging still effective in a sideways market?

I think it goes back to questions like,

• What is the purpose for DCA that particular financial asset or instruments? Is it to get dividend gain through exposure e.g. towards REITs?
• What is the end goal? Dividend gain or trading or investing?

If the idea of DCA to achieve a certain amount of dividend for retirement, sideways market are the best time to accumulate. Plus the idea of DCA is to allow an investor to invest in the financial asset or instruments that they have conviction on for a long term which in turns to achieve a certain set goal.

In short, generally yes when you are investing long term.

I think instead of looking at it the way you framed your question, it's more like DCA was designed to make you not use your brain at all.

It is meant to be a strategy to simply do the same thing over and over again, and not analyze any information on the markets or economic situation, so you don't stress and fuss over whether it's top or bottom or sideways or doomsday.

Still consider dca as one of the key strategies