How come when you have 4 eighth notes in a row, sometimes there all 4 grouped together and sometimes it's written as 2 groups of 2? Is there a difference?
the rule i follow is, never beam more than 4 in a row, and don't beam across the 'imaginary barline' halfway through the bar. so if it's "1 & 2 &" beam all 4. if it's "3 & 4 &" beam all 4. if it's "2 & 3 &" beam it as 2 groups of 2 and leave the middle open. when it's the full bar, beam 2 groups of 4. for 16th notes you can apply similar rules except the 'imaginary bar line' would be between each beat, so again groups of 4 maximum, but don't beam anything across the imaginary barlines