I stand by my assessment that 33:50 is good for a 13 year old.[/quote]
Define 'good'. A 13yo kid in Australia just won his national age-group 3km XC by 20sec, and did 33:30 for a 10km road race (link below). When they had a 1500m relay event two days after the 3km race, a guy he beat by 30sec in the XC came within a second of him in the lead-off leg.
Indeed, a certain amount of base is good, but surely in proportion to your age. What these youngsters are sacrificing is raw speed development. This, along with general strength, plus sharpening technique and form, should be a strong and continuing focus from the beginning. Even, or perhaps especially, if it looks like you will be a better distance runner than sprinter. You need to train your relative weakness, rather than turn yourself into a plodding endurance machine. There are many years to steadily gain more endurance. Lydiard understood this.
http://www.canberratimes.com.au/act-news/a-junior-world-record-20120909-25mlc.html