When firemaking in lines, and there is an obstruction such as a tree or a bush instead of going east one step your character trys to go to otherside or next to the said 'obstruction'. Here is a few pics:
When lighting just one single fire, the following happens.. as it should.
When lighting in a line, as shown below, I ran all the way around the trees. This is shown by the black arrows. (The erased parts are just fires which I erased to avoid any confusion.)
Here is another picture of me going diagonally instead of east when lighting a fire directly before an obstruction.
Also, I know you already know.. but i'll say anyway.. Normal logs really do need fixing since they only giving 1x xp... oaks however do give 2x xp. yay
p.s.. The way 'failing' logs is annoying.. you can do like 3/4 consecutive normal logs in a row and then one will take absolutely forever I know this sounds like this is supposed to happen but not like this. You have to try it out to know I think. I am an experienced player of runescape and have started new accounts for fun many times to know this.