Here is my full answer to avoid repeated characters in urls using lazy match as suggested by samurai8 in previous comments:
FOR REPEATED SLASHS AND DASHES
RewriteCond %{REQUEST_METHOD} !=POST
RewriteCond %{REQUEST_URI} ^(.*?)(/{2,})(.*)$
RewriteRule . %1/%3 [R=301,L]
RewriteCond %{REQUEST_METHOD} !=POST
RewriteCond %{REQUEST_URI} ^(.*?)(-{2,})(.*)$
RewriteRule . %1-%3 [R=301,L]
RewriteCond %{REQUEST_METHOD} !=POST
RewriteCond %{REQUEST_URI} ^(.*?)(_{2,})(.*)$
RewriteRule . %1_%3 [R=301,L]
FOR REPEATED LETTERS IN WORDS
RewriteCond %{REQUEST_METHOD} !=POST
RewriteCond %{REQUEST_URI} ^(.*?)a{3,}(.*)$
RewriteRule . %1aa%2 [R=301,L]
RewriteCond %{REQUEST_METHOD} !=POST
RewriteCond %{REQUEST_URI} ^(.*?)b{3,}(.*)$
RewriteRule . %1bb%2 [R=301,L]
RewriteCond %{REQUEST_METHOD} !=POST
RewriteCond %{REQUEST_URI} ^(.*?)c{3,}(.*)$
RewriteRule . %1cc%2 [R=301,L]
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