If not, is there an easy way to get 90-95% of the way there?

Use bs=1M

It'll give you more than 95% optimal performance over more than 85% your devices, from slow USB2/3 flash drives, SD cards and hard-drives to NVMe SSDs and even RAM-only devices such as /dev/zero.

Source?

Voices in my head.

And some empirical testing over 10+ years combined with pseudo-scientific benchmarking and biased common sense.

Hey, you asked about the easy way!

If not, is there an easy way to get 90-95% of the way there?

Use bs=1M

It'll give you more than 96.3% optimal performance over more than 87% your devices, from slow USB2/3 flash drives, SD cards and hard-drives to fast NVMe Gen3 SSDs and even RAM-only devices such as /dev/zero.

Source?

Voices in my head.

And some empirical testing over 10+ years using dd combined with pseudo-scientific benchmarking and biased common sense.

Hey, you asked about the easy way!

Jokes aside, bs=1M is a good, solid, no-brainer, trouble-free go-to generic default if you can't or don't care about fine-tuning for a specific scenario or device.