First noticed this with sailing. At 100% you're fine, there is no change no matter how often you change direction. If you adjust your speed to, for example, 75 it changes to 74 after submitting it. If you then go back in to adjust your direction (not changing the speed) your speed is reduced to 73 once submitted. And so on each time you click continue from the Alter Sailing screen (you don't even have to change any settings - I just testing that with a sloop and it dropped the speed by 2% each time).
I haven't had a chance to test this on land travel.
Also occurs with projects, but a little differently. I did some testing and it seems that if you have more than enough materials in your inventory then it creates the project as requested. If you enter an amount equal to how much you have in your inventory then it rounds things down by 1.
Example 1: I had 275g meat and a lot of wood in inventory. Set the cooking project to use 275g of meat and let it automatically adjust for the wood etc. When I submitted it using the "only if I have everything" option, the project was set to 274g.
Example 2: I had 500g meat and a lot of coal in inventory. Set the cooking project to 225g of meat and followed the same steps as example 1. The project was created for 225g.
Sorry, I don't have a char I can test this using the "Select how much you want to make" field and ran out of ovens doing the projects above.
