I went 2016 summer, late August. It was a weekend, there was a tiny bit of rain in the morning, it stopped at 12:00 longest I queued was 10 minutes for Liseberg banan. Helix wasn't above five minutes, no one was on Balder and I did all the flats and kanonen (had to wait for more people, RIP to a genuinely underrated ride) got 35 rides, 5 on Balder, 8 on helix, 4 on Lisebergbanan, 4 on Kanonen. I also rerode all major flats about three times and did both water rides and stopped off for a nice meal (a long, but beautiful meal) just under Lisebergbanan. Queues move fast and you'll always be able to reride and hit 25+ rides a day (everyone I know has managed it).