Most of the time it'll be on my computer, especially if I'm doing something that isn't just browsing (listening to music, posting on this forum, checking social media, etc.) but if I'm doing a google search or something, that will always be on my phone, since I carry it everywhere I go and it's convenient to just do a few taps, type something in, and get my answer rather than turning on my computer to check something small. Though most of the time I spend on my phone is either spent on social media or messaging friends.
Would you rather tackle a large task by making a little bit of progress at a time very often, or a few very busy instances?