I think it's a myth too, sorry.
You will get loads of conflicting advice unfortunately as that is the nature of sleep issues, the info is so woolly that there are so many theories, all claim to be "evidence based" and all of them can't be right at once. (Probably they just all fit different babies!) You kind of have to pick one theory and go with that and set a date in mind as in if there is improvement by this date, then great, if not, try something else.
It can be very normal to wake frequently at night at 7 months old. My babies would wake every 45-60 minutes at that age if they were not with me, but if I had them in bed with me then I would get longer blocks of sleep plus it was less disruptive to resettle them. So I chose to handle it that way. I know that is "going backwards" in the theory of trying to make them independent so that they will be more independent in sleep, but I didn't think there was much in that and I felt it was easier to go with the flow.
Sometimes it's helpful just to hear that your baby isn't broken and you aren't doing anything wrong. They do eventually sleep longer on their own I promise. It just tends to take longer than the sleep training books/websites suggest.
If it's every 45 minutes regardless of where she is sleeping, it might be worth ruling out other issues. You say no silent reflux. Any other issues to look at? Allergies, wind, teething, cold? Has it always been this way or a recent change? Is she going through some kind of developmental spurt - working on sitting or crawling? Does she breathe through her mouth when she sleeps?