Try a couple of bananas and lots of water before and water during the trials. Dehydration can mess up your concentration it messes up mine.
On another note I was observing this weekend ( for the first time ) and was amazed at how many riders didn`t walk the section properly !
Eighty percent checked the first time, twenty percent checked the second time then only one or two bothered the third and fourth time.
Standing watching daft dabs because of rocks and branches moving about plus ground degradation from all the riders ! I am defiantly going to be checking every lap from now on as I am guilty of this myself.
Having another look at a section also allows for a small break, especially for those of us who aren`t as fit as we used to be.
All those silly dabs add up.