To add another genie plus experience, here are my measured wait times versus posted wait times for our recent trip. I started the timer when we entered the line for standby and when we entered the line to scan for
lightning lane, and I ended it when we sat in our seats. We bought genie plus 4 days and bought two ILLs, and I thought they were all worth it for two people who visit Disneyland every 5 years or so. Lightning Lane saved us time on nearly every ride, possible exceptions being the times we used it for Splash Mountain and Roger Rabbit. (We saved time against the posted wait time, but I think standby was much shorter at those times.) The grace period of 5 minutes before and 15 minutes after worked for us. Note that around 10 minutes after, the reservation disappeared from my app but our tickets still worked up to 14 minutes 30 seconds. (I definitely don't recommend cutting it that close though, lol.) Also, we were able to book LLs for the other park in the morning before we could hop and it gave us a 1:00 return time even though the posted return time was much earlier.
12/26 (in park 4 pm)
Pirates posted 35 actual 17
RSR posted 120 ILL 20
Guardians posted 40, actual 47
12/27 (in park 8:10 AM)
Space Mountain posted 10 actual 13
Alice posted 5 actual 3
Snow White posted 10 actual 3
Mr Toad posted 5 actual 5
Pinocchio posted 5 actual 2
Storybook Land Canal Boats posted 10 actual 14
Teacups posted 5 actual 3
Small World posted 10 actual 16
Star Tours posted 35 LL 9
Buzz posted 45 LL 6
Guardians posted 90 LL 17
Incredicoaster posted 40 LL 11
Space Mountain posted 70 LL 10
12/28 (in park 7:45 AM)
Guardians from RD actual 16
Guardians posted 15 actual 14
Maters posted 15 actual 12
Toy Story posted 40 LL 5
Pixar Pal Around Non-Swinging posted 5 actual 15
Soarin posted 65 LL 12
Incredicoaster posted 80 LL 8
Monorail posted 5 actual 4
Indiana Jones posted 75 LL 19
Haunted Mansion posted 50 LL 14
Jungle cruise posted 35 actual 30
Railroad posted 25 actual 18
Matterhorn posted 40 LL 7
BTMRR posted 25 LL 10
12/29 (in park 8:45 am)
Jungle Cruise posted 5 actual 10
Pirates posted 5 actual 8
Winnie posted 5 actual 4
Millennium Falcon posted 90 LL 18
Haunted Mansion posted 50 LL 10
Splash posted 30 LL 5
Grizzly posted 5 actual 3
Indiana Jones posted 55 LL 11
BTMRR posted 50 LL 9
Rise of the Resistance posted 80 ILL 15
Splash posted 20 actual 5
Space Mountain posted 55 LL 10
Peter Pan posted 35 actual 36
Guardians posted 30 LL 12
Soarin posted 30 LL 11
Incredicoaster posted 15 LL 5
Monsters posted 5 actual walk on
Matterhorn posted 20 actual 5
Splash posted 5 actual walk on
1/1 (in park 8:45 am)
RSR posted 60 SR 4
Incredicoaster posted 20 actual 14
Goofy posted 5 actual 3
Silly Symphony Swings posted 5 actual 4
Little Mermaid posted 5 actual walk on
Grizzly posted 5 actual 2
Grizzly posted 5 actual 3
Soarin posted 50 LL 10
Haunted Mansion posted 45 LL 19
Indiana Jones posted 70 LL 20
BTMRR posted 20 LL 6
Canoes posted 5 actual 1
Guardians posted 70 LL 18
Roger Rabbit posted 20 LL 3
Gadget posted 20 actual 2
Rise of the Resistance posted 200 actual 108
BTMRR posted 25 LL 5
Pirates posted 15 actual 6
Pirates posted 15 actual 3
Space Mountain posted 30 LL 7
Edited to add: the second BTMRR on 1/1 was from a multiexperience pass we got when Roger Rabbit was down during our original window. We were able to use the pass for BTMRR and also rebook another lightning lane for Roger Rabbit.
To summarize, we waited in a total of 779 minutes (about 13 hours) of ride lines on this trip. We waited 433 minutes for standby vs. a posted 640 minutes, so standby lines were on average 68% of what was posted. We also waited 342 minutes for lightning lane vs. a posted 1590 minutes. If we assume posted times were correct, we saved 1248 minutes (20.8 hours) with lightning lanes. If we assume the posted standby wait for lightning lanes would have a similar knockdown to what we saw (68%), we saved 734 minutes (12.2 hours). This was about $10 per person an hour (or about $7.50 per person an hour not including the ILLs). Another way to look at it is that we saved 12.2 hours and spent 13 hours in line, so lightning lanes allowed us to do roughly twice as much as we otherwise would have been able to.
Edited again to add some more statistics:
Although standby waits were on average less than what was posted, in 8 out of 35 cases (23%), the standby wait was longer than what was posted. The worst case was the Pixar Pal Around on 12/28, when we waited 10 minutes longer and 3x as long as was posted (15 minutes vs. a posted 5). In contrast, for lightning lane we never waited in a line longer than even half of what was posted. The worst case was Haunted Mansion on 1/1, when we waited 19 minutes to get to a buggy for a wait posted at 45 minutes, or 42% of the posted wait. (Note: we got on the HM elevator relatively quickly, but there was a huge buildup between the elevator and the vehicles.)
The max we waited in a lightning lane was 20 minutes, and the average was 10.7 minutes.
The max we waited in standby was 108 minutes (for Rise), and the average was 11.9 minutes. Keep in mind that we mostly only rode standby at the beginning or end of the day and for less-frequented attractions (with a few notable exceptions), while we mostly used lightning lane for the popular rides during the busier times.