In the past, when most people's documents had been accepted by the US government, it would take about 30 days to land an interview in Manila. With this virus, only expedited cases are being processed and those applicants are getting an interview.
In 2019, there were 232,274 immigrant and nonimmigrant visas issued (I'm not sure if fiance and student visas were included in this).
https://travel.state.gov/content/dam/visas/Statistics/AnnualReports/FY2019AnnualReport/FY19AnnualReport- TableIV.pdf
Philippines, Manila
Immigrant Visas____25,770
Nonimmigrant Visas___ 206,504
Total: 232,274
Interviews took place 5 days a week for 52 weeks per year = 260 days worth of interview
So that's 893 visas per day in 2019.
Assuming that 2019 has a similar amount of visas to 2020 and that the embassy has been shutdown since March 17, the backlog is growing.
So in five months, there is the potential to have 89,300 visas not issued because of the closure. There are a few interviews trickling through with expedited cases, but I don't think there are that many visas being issued now.
Reports have shown that the local embassy has a skeleton crew.
BerhaeLee's US Immigration Timeline
July 17, 2020
Embassy Review: USEM is open for US citizen petitioners only. According to my husband, there are less than 10 people inside the embassy and the interview portion is quick.
Don0's Philippines US Consulate Review on July 20, 2020:
"Smooth process but there were only 3-4 Filipino officers and 3 American consuls."
So, this could turn into a situation where you have to wait 6-10 months for an interview in Manila. It's going to turn into a waiting game like the USCIS waiting period. How much backlog will the US Embassy tolerate? Will they hire more staff to help process all these cases?
In the back of my mind, I think I remember reading the US Embassy processed around 300-400 per day, but I can't find the source. Even if it's that amount, that's still 3-6 months of waiting for an interview with this growing backlog.