Does dollar cost averaging only work for ETFs?

Nope. You can dca into stocks through a brokerage like Maybank KE which has the widest range of stocks available for their monthly investment plan. Include other markets like US, Thailand and Malaysia listed stocks as well.

The rationale behind dollar cost averaging (DCA) is the discipline in purchasing a stipulated value of stocks / ETF on a regular basis. It works on ETFs because it is what banks / brokers offer through Regular Savings Plan (RSP) that allows one to automatically practice DCA.

It definitely can be practised on stocks / shares too - Phillip Securities does have standalone shares which they include in their RSPs called Share Builders Plan ( https://www.poems.com.sg/rsp/#home)

However, if one intends to do it manually, one has to note the commission one has to foot

For e.g. If one wants to purchase a $100 worth of RSP / stocks on a monthly basis

Commission % for DCA for purchasing ETF's via RSP = min. $1 (1%)

Commission % for DCA for purchasing stocks manually = min. $10 (10%)

Hence it isn't very feasible practising DCA on stocks through the markets manually