What kind of chart? A bar chart with just one bar? A bar for each day showing the current accumulation to that date?
I think a single bar barchart could be set up fairly easily for this. A different Bar for each day could also be set up, but takes more work to do so...
You can specify a fixed scale, so 0 to 50 can be done, but you can set this via a field so changing the target also requires updating the chart settings manually. It might be possible to chart two bars: 1 would be the actual accumulation, the other would represent the target set for that individual.
If you just specify a scale of 0 to 50, all you need is one record for each days call count and a summary fields that sums the count. Find all records for an individual for one week and chart the summary field. If you need to put multiple individuals on the same chart, that can also be done with the correct chart options specified and some sorting to group records for each individual.