very true, especially with all the sandbagging that goes on in 4/5 racing in the D20 as i'm sure you know. there are definitley some 3s lurking in there, some really good ones too.

those constant sprints ARE what drain you, having to keep up with those leaders on every single corner is the entire point of crits, and you will get super fatigued after doing that every time. the top 10-15 spots are the places you want to fight to be in, as those are where the action happens, and the least amount of turbulence is (hopefully), and where you are less likely to get involved with a crash (hopefully again).

cornering abilities really do go a long way- if you are coming off the back alot, you can make up time in those corners, mainly since individuals or small groups can take them at a much higher velocity than the group. and remember if its a windy course, stay with others!