In my experience, it takes a bit longer to see results on changes done on iOS than on Google Play.
For Google Play, I often see an almost instant effect on changing metadata, for better or worse, which also allows us to react faster if more adjustments are needed, or if we want to revert. And as metadata changes don't require a full update with review on Google Play, changes can be implemented quite fast.
On iOS it takes a bit longer, and sometimes up to 6 weeks, but the more drastic changes seem to be visible somewhat faster. When experimenting with new keywords and keyword combinations, I still usually let them run for 6 weeks before evaluating the results, especially if it is a keyword that we presume could have a significant positive impact on the search results, for example, based on a high search volume. However, if the keywords are more experimental or related to trending keywords or special seasons, like Halloween, where the chances of ranking high enough for it to have an impact, we often move on to new keywords even if it has been less than 6 weeks.