I finished cart ages ago, i posted how in another thread:viewtopic.php?f=9&t=18882&p=166046&hilit=cartography#p166046
For the record, rammar, cart isn't difficulty based so it makes 0 difference which map you make from 0-GM. Someone should update the wiki already.
I thought not, as I had fairly consistent gains regardless of which map I made when I checked in on it. I did most of it while I was sleeping though, so I wasn't completely sure.
This doesn't apply to decoding tmaps though does it? A lvl1 will not give as much chance to gain as a lvl4 when at 90 skill.
Correct, you can get good gains from decoding maps that you've only just reached the appropriate skill level for, since they are difficulty based. Likewise you can't gain cart from a level 2-5 map when you haven't reached the appropriate skill level.
I left my lv4-5 until I was 99.5+ as it's still fairly easy to gain from doing regular carto even at 90. The gains in the last 10-20 points can take up to an hour for a single gain from creating maps, IIRC. You can still fail to decode lv3 at GM, so you could even gain from lv3 maps to GM (which are more difficult to decode than using the skill itself, yielding better gains even in the upper 90's).