I think you are querying Fight Aids at Home phase II work units so you could be in the wrong forum.
I do not know how to refer to a previous post so here is a copy of the reply to a similar post there:
The following is from memory and not searching the forums.
When FAHB was first introduced a work unit consisted of 100,000 steps with a trickle up process every 10,000 steps. The next work unit was generated using the output from the returned work unit. A complete ‘unit of work’ consisted of a chain of 10 work units. Each work unit had a 10 day deadline so the complete chain could take about 100 days. Each work unit needed 10 to 15 hours CPU time to complete on a reasonably fast machine (I7-6700).

The project had strange rules which caused the server abort of running work units if the server considered the work unit would not complete before the deadline which was not always popular.
The trickle up process also caused problems for PCs which did not have a permanent internet connection as the upload of the completed work unit had problems if all the trickle up results had not been processed. There were also problems when the upload servers were not available due to maintenance at WCG.

The current work units avoid the above problems but have the disadvantage of the 1 day deadline and the allowance of one work unit per thread. There are two types of work units which contain either 10,000 or 50,000 steps. Looking at my results I can see a 26th generation work unit of 50,000 i.e. 1,300,000 steps. The highest 10,000 series work unit I can see is only 32 generations (but I seem to remember much higher generations in the past) which is 320,000 steps.

I hope I have remembered correctly.

Was it 10 or 4 days, including repairs for the trickle version?