For travels through a NPC dialog with zeppelin/boat/train/submarine:
- It is Day 5, 6H59 AM, you travel, then you arrive day 5 7H AM. Travel took 1mn.
- It is Day 5, 7H01 AM, you travel, then you arrive day 6 7H AM. Travel took 1 day minus 1 mn.
- Take care of the animation trick I quote, if you don't skip them some will use more than 5mn of game time.
- There's one and only one exception to this rule, it's the travel to go to Turtle island, for this case your travel will only take the game time to run the animation. But the travel back from Turtle island to Darion follow the standard 7AM trick.
About playing it linear, well there isn't only one way to do it. If you want make a 7 day game there's certainly many margins there and there and many alternate choices.
One of the more challenging area for the game time point of view is Darion. But you have choices and that depends of your game. To win the maximum time there's no secret you rely on finding fast enough Gift + Inquisitor or Resurrection. To win even more time you rely on finding sacrifice that allows increase your stacks without many walking. So if you find soon Inquisitor + Gift + Sacrifice you can save a significant game time, in this case you get more margin.
In my game I didn't find Sacrifice until Freedom Islands and had inquisitors and Gift in Swamp only. So I tempered this by many little tricks and one of those tricks was to not rush to the rage box to save many walk. But the price is huge because of the tactical plus that gives Sleem in the game beginning. One thing before getting Sleem is probably to be sure you'll really get profit of it. I think you need have at least rage of 20 otherwise in most first battles it will be useless if you are a mage. If you are a warrior rage fill up much faster and this can be tempered. Myself I set my limit to rage 30 before go to rage box in urge and this had the effect to not change my path at all for the rage box. But even for a mage the alternate option is a possibility to look at. For a warrior the point of view is clearly different.
The better is to try different options by yourself for the game you selected. If I remember well I played 3 times the same game before Freedom Islands until I find a fair way to manage Darion and game time.