Last week I had great luck booking SDD first, then Rise. Even if Rise looked sold out at 7:05 am, bunches of slots would appear later, and those didn’t disappear nearly as quickly.
For my HS days, I Genie-dropped Slinky right at 7:00, and got times of 10:50 and 10:20 respectively. For Rise, the first day I fell victim to the “booking failure” glitch and was locked out of purchasing until 8:00 am. However, even then I was still able to get a 9:45 ILL, and saw tons available later than that. The second day I wasn’t planning to ride Rise at all. However, when I got to the park for EE and walked by it on the way to MFSR, I changed my mind. (Yeah, being at Disney does that to you!) Checked my tip board and was able to get an ILL for 1:55 pm - this was at 8:30 am.
The moral is that even if the ILLs look sold out, keep checking back. From what I saw, this works better for Rise than for Slinky.