I’ve tried using 3 of a colour and got frustrated. (Readers of my other posts on this board will know that I frustrate easily, so maybe that opinion doesn’t count for much).
Looking at it more logically:
If you now eliminate 2 other effective colours from the board, I would say you are more statistically likely to get unfavourable boards than favourable. So although I think your highest individual score would be much higher with triple colour (for the odd time you get a favourable board) I would expect your average score would probably be lower. Each time you get a favourable board in the off colour, you are getting very little score, which would not make up for the occasional time you get a good layout in your tripled colour. You essentially have double the chance of getting a good layout in 1 of your 2 missing colours to what you have in getting a good layout in your triple colour.
This is gut feeling… I don’t have the statistical grounding to definitively prove this statement. It boils down to the forum equivalent of a drunken ramble in the pub.