Inconsistent Spelling in the Great Isaiah Scroll

It is important to realize that spelling was not standardized or consistent in many ancient manuscripts. I came across a good example recently from 1QIsaiah(a)--The Great Isaiah Scroll. The Hebrew adverb for "very" is spelled three different ways in the manuscript: מואד in 16:6; 56:12; מאדה in 31:1; and מואדה in 47:6, 9; 52:13; 64:8, 11. These were all apparently written by the same scribe (though there is some debate) within a relatively short period of time. There also do not appear to be any obvious patterns, since the different spellings are scattered about the manuscript, so this example does not support the assertion that the spelling drastically changes in the second part of the manuscript. There are many such cases, even some with more variants (Kutscher Language and Background of the Isaiah Scroll 166-7, lists, for instance, ראש-רואש-ראוש-רוש and זות-זואת-זאות-זאת, among others). We should not necessarily expect to find, therefore, consistent orthography in biblical manuscripts.