Harness lines lenght is something very personal, so I don't think this is something universal. It also depends on your size x weight, boom height, type of harness, type of sail and board and fin size.
For my 183 cm x 65 kg frame, this is what I'm using :
- 11.0 m2 racing sail on Serenity : boom shoulder height, 32" long harness line, race seat harness, low hook (better leverage with my light weight);
- 11.0 & 8.2 racing sails on HS105 : boom chin/nose level, 32" long harness lines, race seat harness, low hook (better leverage with my light weight);
- 6.6 racing sail on HS105 : same as above except 28" long harness lines;
- 6.9 freemove, 6.2 & 5.4 wave sails on Kombat 86 : same as above except boom at shoulder level for freeride blasting.
- 6.9 freemove, 6.2 & 5.4 wave sails on Kombat 86 : boom at shoulder level, 28" long harness lines, wave chest harness, high hook for waveriding.
- 5.4-3.3 wave sails on Acid 62 : same as above.