"progresses gradually" is a correct and usable phrase in written English.
You can use it when you want to describe something that is developing or changing slowly or over a period of time. For example: "The baby's language skills progressed gradually, until he was able to form full sentences."
There is no cure, but the disease generally progresses gradually and does not affect life expectancy.
And Kiera, as Season 1 progresses, gradually confronts the possibility that she is fighting for the wrong side.
The mapped contoured surface should not contain discontinuities, so that the level of hazard progresses gradually and in order across any profile drawn on the map.
The hair loss in male pattern baldness progresses gradually, beginning with a characteristic recession of the hairline at the front or thinning of the crown hair and proceeding, in extreme cases, until only a thin rim of hair remains at the sides and back of the head (the "Hippocratic wreath").
On the other hand, it is thought that this reaction progresses gradually from the surface of the hardened cement paste attached to the RFA towards the inside, causing the cement matrix to become denser.
This unusual clinical presentation, most notably incidentally discovered adrenal hyperplasia, progresses gradually throughout the life cycle, and clearly differs from that previously described during primary glucocorticoid resistance associated with other NR3C1 missense mutations.
Sex would progress gradually from kissing to petting and beyond.
In the play three stories are interwoven and progress gradually from the ordinary to the fantastical.
This was a formal reunion, expressing in a few hours a process that has progressed gradually over the past few years.
Even so, morphological evolution would not always keep progressing gradually, because some forms, at least, remain unchanged for extremely long times.
The Moyamba treatment centre is little more than a patch of cleared ground at the moment and will not open until 15 December and, for safety, will only take 10 patients at first and progress gradually to 100.
