I've found some more scientific papers/research on the subject.
All of them concluded that growth happened in all of the patients. The difference in growth speed mostly had to do with low use of the system (both in time per day and in weeks/months of use). There is also a minor, less obvious difference, in patients will lower starting breast volume or a low body mass.
Since the results of Rocketmelon are an outlier, probably because of a combination of nbe treatments, I decided to exclude her results. Her % increase per hour was 0,164% and her cc increase per hour was 0.641 cc.
When including this new research, and excluding Rocketmelon, the average % increase per hour is at 0,088% and the average cc increase per hour is 0.206 cc. Her % increase per hour is twice the average rate, which is possible, this also happened in other studies. But especially her cc increase per hour is high, more than 3x higher than the average. This is probably because she continued nbe to a very large size. If the % increase per hour stays the same the cc increase per hour goes up. 1% of 240 cc is 2.4 cc, while 1% of 1000 cc is 10 cc.
The % per hour increase of the studies are very close and several studies mention that initial starting volume is a minor influence. So this, and the difference between Rocketmelon her % and cc increase per hour, make be believe that the % increase per hour is more important to get a good idea of your growth rate than the cc increase per hour.
Anyway, more scientific proof below!:
Induction of Adipogenesis by External Volume Expansion
https://www.ingentaconnect.com/content/wk/prs/2016/00000137/00000001/art00032
This research proves that the concept of tissue growth through external volume expansion works.
It’s is a short-term study of only 5 days on mice. They used an “external volume expander” for 2 hours per day with a pressure of 25 mmHg. Even after a single treatment of 2 hours they noticed an increase in edema and amount of adipocytes (cells that create and store fats).
The Brava external tissue expander: is breast enlargement without surgery a reality?
www.ncbi.nlm.nih.gov/pubmed/18040206
This research proves that growth is possible and sustained 10 months after using the device.
This study followed a group of 50 women, of which 10 dropped out. The remaining 40 women used the Brava external tissue expander for up to 11 hours per day. The device was used for 14-52 weeks, with a median of 18.5 weeks. During a follow-up 10 months after use the volume increase was between 95-300 cc, with a median of 95.
Factors associated with poor growth: low body mass index & lower intensity use of the system.
Nonsurgical breast enlargement using a vacuum brassiere for tissue expansion
https://pubmed.ncbi.nlm.nih.gov/16285326/
This research proves that growth is possible and sustained 3 months after using the device.
This is a single patient study in which a “brassiere-like system that applies a vacuum force” was used for 10.6 hours per day over a 10-week period. The pressure used was 20.4 mmHg. Initial chest circumference grew by 5 cm at the end of the therapy. During the follow-up, 3 months later, the edema subsided and a stable 4 cm increase in chest circumference remained.
Multicenter Evaluation of an External Tissue Expander System (Brava) for Breast Enlargement
https://asps.confex.com/asps/2002/techprogram/paper_1111.htm
This research proves that growth is possible and sustained 3 months after using the device.
The study followed 95 women which used the Brava systems for 10-20 weeks (average = 13 weeks). Breast volume increase was between 30-250 cc (average = 108 cc) or 11-290% (average = 80%). According to the researchers there seems to be a small effect from the original breast volume and the body fat index, but the largest effect came from compliance (the amount of time the system was really used) and the duration of the treatment period.
Nonsurgical breast enlargement using an external soft-tissue expansion system
www.ncbi.nlm.nih.gov/pubmed/10845308 (mentioned before but only as a link)
This research shows that growth is possible and sustained 30 weeks of using the device, that the long-term growth comes from new gland & fat tissue and that it’s possible to lose weight while increasing breast size.
This study followed 17 women, of which 5 dropped out because of noncompliance, which used a tissue expansion system with a 20 mmHg vacuum for up to 10-12 hours per day during a period of 10 weeks. Breast size increased in all women. 30 weeks after use the range of increase was 15-115%, with an average increase of 55%, despite the women in the study losing a statistically significant amount of weight. MRI scans showed no more signs of edema (swelling) and confirmed that the stable increase came from the proportionate enlargement of adipose and gland tissue.