You may be right, it would depend on the shrub. More importantly though, English Ivy tends to a menace; it will take over your lawn, trees, and even your house. And once it's established, getting it out is impossible.
The only way it will harm your shrubs is if you dont have good healthy shrubs otherwise it will just grow up and crawl in and around them and all will be well. For details do a web search and it will pull a ton of information.