Sometimes - more often (especially if I'm at one of those Cambridge junctions where there's a cycle lane going right but they conveniently forgot to add traffic lights or lanes for cyclists turning into it) there's a stream of traffic going past slowly but close enough that it's dangerous to stick my arm out in the first place until there's a gap where I can do the whole indicate-pull-out-turn before the next thing coming the other way. This is especially the case going into Downing Street, and I would rather go round the other 3 sides of the square and make it a left turn than do that right turn.