[beetcleaner]

Further to my previous post and the excellent advice given could I ask a quick question on split grade printing?
I've ordered a set of below the lens Ilford Multigrade filters for my Durst M370 Colour enlarger because I'd like to try this technique.
I know I could use the built in filters but for a novice I think a filter kit would be simpler to get started with.
As an example if I do a test strip with a MG 2.5 filter and the best exposure is 6 seconds, then my understanding is I split the exposure for 3 seconds with a MG 00 filter and 3 seconds with a MG 5 filter.
However I notice that if printing with a single MG filter then the exposure time remains the same from MG 00 up to MG 3.5 but then from MG 4 upwards the exposure time is doubled.
Does this also apply to split grade printing? ie in the aforementioned example would I use a MG 00 filter for 3 seconds and a MG 5 filter for 6 seconds?
Is it also the case that to increase detail in the highlights I move up the filters from MG00 to MG 0.5 or MG 1 and to increase detail in the shadows I reduce the exposure time with the MG 5 filter rather than moving down to a MG 4 for example.
Thankyou for any advice