Say if I have around 5 websites already up which is making a good amount of profit... most of my time would be going into that therefor I wouldn't have time to do all the SEO work? Would you recommend a monthly service?
You're speaking in hypotheticals.
You don't get 5 sites 'up and making profit' unless you understand SEO, OR hire someone directly who truly understands it on a zoomed-out level (and pay him or her the $150k+ that he or she demands, and is worth). Therefore, worrying about what might fill your day at an indeterminate point in the future is possibly not the best focus for you right now - I suggest the best focus is figuring out exactly what steps need to be taken to get the first of the 5 sites 'up and making good profit'. SEO is really not difficult, so don't shy away from understanding it inside and out - it's just about building links, with the only variable being what kind of links you build, and in what quantity.
Please don't take what I say as criticism or an attack - it's certainly not intended that way, rather, it's intended to help you focus on what puts cash in the bank account, and that in my view, is the ability to rank sites. That said, I don't have a monopoly on truth, and I'm sure there are plenty of other ways 'to roll'.
PS - given that I think the real money maker is the ability to rank sites, I put it to you that the best use of an IMers time is in fact the SEO aspect, rather than any incidental operational aspect of a ranked site. There are plenty of (cheap) workers available remotely to do whatever cookie-cutter tasks might be involved in delivering a service or product that is sold on your site, but, nothing gets sold if it's not ranked - which therefore loops back around to Mission Critical Step #1 - ranking your sites!. So, spend your time on mission critical, and let task-workers work the tasks.
EDIT: PPS - you said 'wouldn't have time to do all the SEO work'. I have dozens of sites, and I 'do all my own' SEO, but I don't do any SEO work. I decide what needs doing, then I order from service providers, or I have my VA's do it.