It really depends on the battery I think.
I think the safest way for any nimh is to leave abvout a 25% charge in them for storage, and the night before you race discharge them to 5.4 volts. Make sure to use a tray to equalize them after you discharge them after each race. Watch the tray and remove the load on a cell as the light goes out.
That is what I have done with my nimh's so far, I have owned all 3 panasonic, and both sanyo 3000s.
I don't have any of the newer 3300's yet, care for those may be different.