Check, then Observe
Please use the Search page before you start work on a target, not after you have several sessions. This can help avoid unneccesary duplication.
Some times duplication is good because the period cannot be effectively covered by one station or those of similar longitude. However, some times that single station can and does cover those more difficult objects by sticking with it a little longer. In the meantime, there are thousands of asteroids within reach of backyard telescopes that have no lightcurve parameters at all and dozens that are wanting only good coverage at one more apparition for modeling.
The CALL site's value as an observing tool is up to the observers. If used effectively, we all benefit as does asteroid research. If poorly used or abused then, like any tool, it eventually breaks and tossed aside.