When you are depending on that graph you need to have a more time so you can really manage not to lose money in trading and save some extra bitcoin in the next dont panic when the price is low wait for it always to be high again and everything will be fine.
waiting for the price to rise high sometimes just working is it does but i'd prefer to cut lose if the specific coins seems don't have a good future to prevent from having such a big lose like zcash which had been falling down recently from 1btc to about 0.3btc and that's such a pain in the ass
yes that is a fact that some time booking a little lost is good as it can prevent you from making a big lost, therefore you must always be careful while taking a decision as some time your lost can be proof as good for you .