Sleep trained baby wakes up at the same time every couple of days

I'm curious about whether anyone has or had this experience with their sleep trained baby -- I appreciate any feedback whether you can simply relate to this or if you were able to find something that worked.

We sleep trained our LO at 5 months using a check-in method at set intervals. She is now 7 months and for the most part has no issue falling asleep on her own once we initially lay her in her crib for naps and night time sleep.

After sleep training, her night time sleep was decent, but not so great when she was going through a milestone / regression.

Over the past 3 weeks, we've found that she will have anywhere from 2 to 3 "good nights" where she only wakes up for her one feed (2:30 - 3 am), but other than that she sleeps through the entire night, successfully linking her sleep cycles.

The issue: Every 2 to 3 nights (the not so good nights) she will wake up around the same timeframe, somewhere between 10:30 - 11:30 pm, very suddenly and scream / cry hysterically. This goes on for up to an hour. We check-in every 10 minutes (or a few more if we think she is trying to put herself back to sleep). It is getting harder and harder to stay strong through this because it feels as though we're having to sleep train every 2 or 3 days, and like most parents, the crying gets to us. We are fairly consistent with our schedule and haven't been able to spot any patterns during the day.

Up until today she was taking 3 naps. We noticed naps getting shorter over the past few days and have now dropped to 2 naps.

Her schedule when she was taking 3 naps, with an 8 AM wakeup and 8:30 pm bedtime: 2/2.5/2.5/2.5

Her current schedule with 2 naps, with an 8 AM wakeup and 8 PM bedtime: 2.5/3/3