Can one “theurge” prestige class cause four different progressions?

Question

After reading a level-up table that mixed theurge classes, I've become confused about how said classes work. Lets say that I'm a multi-classed Bard/Wizard/Cleric/Paladin/Mystic Theurge of some level that used his first level of Mystic Theurge to advance Bard and Cleric and who is about to take his second level of Mystic Theurge. Can I use said second level to advance Wizard and Paladin?

For reference, I'm aware that the description of the Mystic Theurge states "If a character had more than one arcane spellcasting class or more than one divine spellcasting class before he became a mystic theurge, he must decide to which class he adds each level of mystic theurge for the purpose of determining spells per day", but that doesn't tell me if that means that I can pick and choose at each level or if that means that I'm locked in to the choice that I made at entry in to the prestige class.

Answer 1

When the class feature spells of the prestige class mystic theurge says, "When a new mystic theurge level is gained, the character gains new spells per day as if he had also gained a level in any one arcane spellcasting class he belonged to before he added the prestige class and any one divine spellcasting class he belonged to previously" (emphasis mine), it really does mean that the spellcasting advancement is discrete and unique each time a new mystic theurge level is gained.

This is, by the way, in addition to the spells class feature saying, "If a character had more than one arcane spellcasting class or more than one divine spellcasting class before he became a mystic theurge, he must decide to which class he adds each level of mystic theurge for the purpose of determining spells per day" (emphasis mine).

Thus taking 10 levels of mystic theurge and advancing cleric casting and wizard casting by 10 levels is just as legit as taking 10 levels of mystic theurge and advancing 5 different classes' arcane casting by 2 levels each and 5 different classes' divine casting by 2 levels each.

For example, an epic character could be an archivist 1/beguiler 1/cleric 3/druid 1/duskblade 1/favored soul 1/hexblade 1/mystic 1/trickster spellthief 1/wizard 3/mystic theurge 10 and have used levels in mystic theurge to advance each of his casting classes by 2 levels each. However, despite possessing 24 characters levels, such a character will be woefully ineffective in all but the most unusual campaigns, surviving—if he does—largely due to his player's careful spending of his enormous gp budget.