I have fired hundreds of kids' ceramic pieces without a single explosion.
This is not because my students have made "perfect" constructions but
because I slowly bring my kiln up in temperature, especially in the early
stages of the firing. Most kiln instruction books assume that you are firing
thin, even slip molded ware which is very different than hand built or wheel
thrown works (especially beginner works). My firings are a minimum of 12
hours (to bisque cone 010) preferably I start the kiln on low (sometimes
just one switch) the night before firing. Another tip: ALWAYS, ALWAYS use a
cone in the peephole for visual observation as a backup for any automatic
shutoff systems (cone-sitters et al.) and check that the auto system has
functioned properly before leaving the kiln for the day (or overnight). All
of those systems wear out eventually and you will ruin all of the work in
the kiln as well as do damage to the kiln and kiln shelves when it overfires
significantly . Hope this helps!