I'm only doing reposting, so for me its easy to manage my accounts. Just find content and repost it with proper credits and hashtags.
Takes me between 5-10mins each time, 3-4 times a day
I'm not sure what's your query here. But if you're asking how to run multiple accounts then you can do it on the same phone. I run 3 main theme pages on my main phone. I'll also advise you to start with one niche and create multiple authority accounts in the same niche, creating a network of accounts in the same niche is easier when you're starting out.