Accumulation bitcoins gradually with time is a good investment strategy as it will help you to gain many things simultaneously.

Increase your total capital spent in bitcoins as your investment.
Reduce impacts from price volatility.
Increase your portfolio ROI in a bull run because Bitcoin stays around bottom range with a longer time than how it stays in peak range in a bull run.

You will have more time to accumulate bitcoin than time to take profit in bullish months within a single cycle.

Your accumulation is only healthy and sustainable if you don't use all money you have at any specific time to invest in bitcoin. Because you always need to have money in either cash or stable coin to use for many necessary and vital things in your life.