7 strand 25mm, already having spent ages routing and shaping. In most cases I do trim the conductors and no problem. In the few cases where I'm routing in, a slight trim will make the turn-in too tight or just give me a head trying to get the bend in, always dependant on where the lines are coming in. Straight in from north or south never an issue, but in the west/east cases I end up shrinking, to be fair we're only ever talking about a mill of shiny copper, but forcing that mill out in an already shaped bend requires serious weetabix.
But putting the above aside. I know in HV cases they do use adhesive lined shrinking, though never seen it personally in LV. Saw the old guy doing it on a couple of occassions and thought I'd ask what others thoughts are on this. Nothing in the regs I can see regarding adhesive-lined shrinks.