Hello Elizabeth, If I understand you correctly, how a DNA bar fills up can vary due to the type of DNA test. One Y-DNA test would fill the bar 50%. Matching Y-DNA tests of direct paternal line relatives would fill the bar 100%. Similar for mtDNA. Two auDNA tests for matching 3rd cousins or closer (who share the expected amount of cMs for their relationship) would fill the bar 100%. auDNA matching between two more distant cousins would fill the bar two thirds. Three or more distant cousins who all match each other on at least 7cM would fill the bar 100%. X-DNA is similar to auDNA except when two male cousins share on the X.
This seems a bit complicated to me (unless WikiTree is able to completely automate it). Sincerely, Peter