That's how I would do it. Just ice and water the whole roof and shingle it.
But I wouldn't do it on a large roof section, because I have heard of cases
where it failed. I have, however, done small porch roofs this way
(including on my own house) and they didn't leak.
But it is risky, and if it leaks don't be surprised.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.