It is not a myth, but it would be pretty impossible to lose half of your zodiac quest exp, since it is doled out in chunks (as are a number of large-scale quests.) The formula is this, when questing:
A quest exp reward cannot exceed the total exp that a player already has.
Some of you might hear this and go WHOAOAA!! I'm sure I lost a ton of exp because of this!!
No, that is extremely unlikely, even if your character was made a long time ago before the tutorial was created. The reason is this: a brand new character begins the game with exp far exceeding what most tour-sized quests offer. Likewise, most quests of any real size require at least a few skills to be trained, and many require certain stats to be achieved. What is more, most characters have done at least a bit of killing between creation and their first really large quest, which almost guarantees that they would have sufficient quest exp to have their reward not exceed their total.
The rationale for this rule is something of a carryover from the older philosophies of game design that were prevalent when the bulk of Genesis content was created. This was a time when quest runthroughs were not only discouraged, they were illegal. This mechanic was inserted to prevent a scenareo where a new character is created, heaped with money from a friend to train skills, and then run through some big quest right off the bat to give them quick size.
I question the value of this mechanic in today's game, but due to the nature of Genesis organic design, to change it would require that the code for each quest be individually sifted and altered one by one. This may someday happen, especially if we eventually get around to fixing up all quests to make them more friendly in terms of syntax and sequential logic (a long-standing goal, but quite an ambitious one.)
So ... all that being said, with a new character these days, the solution to all of this is extremely simple: do a few small quests first, and you'll be fine. Completion of the tutorial alone would guarantee safety from the tyranny of this mechanic. So ... Bendis was correct, Cherek!
G.
Mmmmmm ... pie ...
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Who could help and publish their favorite quest order?