The word もっとも has a few different uses. For example, jisho.org lists the following:
最も(もっとも)
Adverb
- most; extremely
Other forms
最も 【もとも】、尤も 【もっとも】、尤も 【もとも】
尤も(もっとも)
Conjunction
- but then; although; though (Usually written using kana alone)
Na-adjective, Noun
- reasonable; natural; just (Usually written using kana alone)
According to super daijirin, these words have the following pitch accent patterns:
最も: もっとも{LHHL}
尤も: もっとも{LHHL} or もっとも{HLLL}
Considering that 尤も has these two potential pitch accent patterns, when should もっとも be pronounced as もっとも{LHHL}, and when should it be pronounced as もっとも{HLLL}?