It is a waste of time but can be a fun waste of time :slight_smile: , and it is a bit predictable so you can work towards a favourable tint that does not come in a single led. But as said above, expect no miracles like improving CRI compared to the individual leds used in the mix.

Edit: the last is not completely true, I once mixed a 80 CRI 2700K Cree XD16 with a 625nm red led and when the ratio was tuned a bit the result was I believe 2300K and 92 CRI. The reason was that the CD16 was well above the BBL and clearly lacking in red, the red led quite precisely filled that gap in the spectrum which improved the CRI drastically. As you noticed, household bulb manufacturers use that trick also.