With so many ARFCN available, you don’t need to worry. It would be interesting to keep 5 to 8 ARFCN not used, for future TRX extension, or new cell integration.
The way to split the band between BCCH and TCH depends on how many TRX per cell.
My example was for 4 TRX per cell, in which case you give 30% of band to BCCH and 70% of band to TCH.
In your case, with 6 TRX per cell, I would give 20% to BCCH band, 72% to TCH band, and 8% free, reserved for future use.
There is now several automatic frequency planning tools, based on radio measurements. It’s usually a tool provided by the vendor (EFO for Ericsson for example). I’m currently using extensively EFO for creating frequency planning on ALU, Huawei, Ericsson on Nokia networks. The results are just incredible.
It’s way more efficient to do a FP using such tool rather than doing it manually. And the resulting KPI… well, they are amazing 🙂