At this point I don't think even the scientists know how many WU are going to crunched. They have not yet analyzed all of the data from Phase 1. I am pretty sure they are using the results from Phase i to generate the WU for Phase 2 by looking at the most promising candidates from Phase 1 and further refining the results. This phase is taking a much deeper look at the identified molecules, hence the much longer run times per WU and the sequential nature of the project, each WU dependent on the one prior to it until 3 to 4 million steps are completed.
Just as an aside, the average WU on one of my machines takes about 19 hours. If all 30 steps were to be done as one WU, it would take about 570 hours or about 24 days. I am sure most people would not want a single WU which would run that long. I know some of the climate sciences have some which run much longer.
Cheers

The researchers do not yet know when they will complete the evaluation of Phase 1 results, nor do we know the exact number of work units there will be for Phase 2. Please check the status bar on the Active Research page for progress of Phase 2, and when there are updates on Phase 1, they will be in the News section.

Thank you,
ErikaT