If my (enthusiast-level) understanding is correct, on instrument approach there are specific glideslope paths a plane is expected to follow. On ILS this is self-evident, but (again, if I read approach plates correctly), VOR DME approaches also entail a certain altitude that must be crossed at given DME distances. I assume, crews estimate their rate of descent based on their ground speed etc.
Now, when visually, apart from PAPI lights, is there any other way of estimating the correct glideslope? With C172s and 55 knots, I expect it's easier to simply crawl to the runway and adjust accordingly. But how does it work when you have a B737 or A320 landing on a 6000ft/1800mt runway without PAPI lights? I expect a certain kind of precision is required, but does it come merely with experience, or is there some other way?