Personally I think you going of the rails by adopting a all or...

Personally I think you going of the rails by adopting a all or nothing approach. Sure this is pretty much spot on from a traders perspective buy a position at some low point and sell at a chosen and possibly predetermined take profit or at/near the high.
As a determined and committed LT holder IMO the aim is to use some of your stock to trade with, in order to reduce the buy-in price to a lower buy-in average and/or eventually reach a very low or even free carried holding, with no or very much smaller capital exposure/capital risk. It is a kind of trading however it hardly influences the overall SP, but returns capital to where it is safest, your trading account. This in turn then can be used to again buy the dips or if other opportunities possibly even better present themselves they can be taken up in order to diversify one's holding and reduce risk that way.
I hope the above does makes sense to some!