Assertion:
If you use a BR at the end of a block structuring element (ex: BLOCKQUOTE) or block structuring sub element (ex: LI), you may need to use two consecutive line breaks to produce a visual space in a document. This is because there is already an implied line break at the end of block structures.

Simple UL list:
filler text filler text
Simple UL list with one BR at the end of second LI:
filler text filler text
Simple UL list with two BRs at the end of second LI:
filler text filler text