I guess it depends on wehat yeast you are using. I mainly use Nottingham which floculates very well and so it keeps together as a tight pack when the beer is opened and poured. It also depends on the bottle. I used to have that problem with Nottingham when I used old plastic sparkling water bottles.I used to fine PBs until I discovered that the beer would drop bright anyway. The few time I tried fining bottles was a disaster as the yeast lifted into the beer on opening the bottle.