A very common usecase of forms is to send a download link afterwards. (for whitepaper download links for example). By doing so, people are basically required to enter a legitimate email, which helps with spam and keeping our database clean. However, the inbound customer journeys (customer journeys in general too) timing is so irreliable that we can't use this feature. (Even though Microsoft uses this example as well on their website: https://docs.microsoft.com/en-us/dynamics365/marketing/create-inbound-customer-journey)

My suggestion is to make some sort of feature/improvement so that we can use a form on a website and then automatically send a marketing email with a download(link) afterwards without delay. The timing can now differ from several minutes to hours and no customer is going to wait that long. I did notice improvements, but this is something relatively simple in my opinion that should work all the time. Thanks! :)