早期韻圖為咗結構整齊勻稱，或者係爲了節省空間，或係拘泥於傳統嘅等韻學概念（如「五音」、「三十六字母」），經常將特殊嘅字音安排到特殊的位置，在整體佈局之外造成了非常多的特例，如：「聲母分等」破壞咗「一個聲母一列」的原則；「去聲寄此」破壞咗「四橫欄對四聲」嘅原則，等等。其結果就係，讀圖者好難掌握與所有特例相關嘅細則，因而往往無法通過某字所屬的行列得出其正確的讀音來。
In order to have a neat and symmetrical structure, perhaps to save space, or to stick to the traditional concept of isophony (such as "five tones" and "thirty-six letters"), the early rhyme diagram often arranged special sounds in special positions, which caused many special cases outside the overall layout, such as: "Initials are divided into equal amounts" destroyed the principle of "one initial, one column"; "Sending this" undermines the principle of "four horizontal columns to four tones", and so on. As a result, it is difficult for the reader to grasp the details relating to all the special cases, and thus it is often impossible to derive the correct pronunciation of a word from the ranks and columns to which it belongs.