The pre-made guides are a good method instead of crimped in 90s. There is almost always room for them and no chance of a fitting failure. If the bend radius is not so critical just bend it around and snake it through as needed. The 1/2" PEX (5/8" OD) can be reliably bent into a 9" O.C. return bend with no kink. Once bent it will not relax into a kink. Also, if doing the guides, you don't have to get the crimp tool into place and use it. The flow characteristics are also a lot better with bends instead of crimped 90s.
Pex is surprisingly nice to work with. When working with PEX, think in PEX instead of copper.
Another trick is to slide the PEX through conduit 90s. 1/2" PEX (5/8" OD) slides nicely through 3/4" electrical conduit 90s. 3/4 PEX through 1" conduit 90s and 3/8" PEX through 1/2" 90s. Steel or PVC conduit works fine for this and seriously protect the PEX. Always use brass fittings and copper crimp rings. Always.