Is there a way to speed up the flow of a stream so the user gets the emails faster? For example, there could be a link in the email they can click to speed it up, and it would automatically speed up the emails.
Once they are in the flow, it is best practice to not touch the flow because things can get weird. If they click a link, you can always trigger their removal from that campaign and put them in a campaign that sends emails more frequently.
You can also add constraints on subsequent steps that allow them to move though more quickly e.g. On wait steps. If this is an active campaign I would also suggest creating a different campaign that you can add them to. - Jeff