Coming here to provide an additional data point. I transferred about 4K Marriott points to Alaska to be able to book an award flight. Took about 3.5 days to process (I did the request just after midnight on 26 May; miles just posted within the past couple hours today, 29 May). Thankfully the Award Space was still there (was a booking on AA flight with AS miles) so I was able to get the flight I wanted at a decent rate (and way better rate than what AA was charging on the same flight with AA miles).