While saving 6 months might be possible, I would love for you to point me to a high-yield savings account.
[0]https://treasurydirect.gov/indiv/products/prod_ibonds_glance...
However, if one wants to hold a portion of bonds and a sub-portion of said bonds happen to be I-Bonds, then I see no issues with that.
Nonetheless, the point is more that: you need risk-free cash to live sometimes, keeping 6 months of your current costs in a low-risk account is pretty base levels of financial literacy