Not related to your question, but your oscillator may start better if you use an odd number of inverters; although, using a Schmitt inverter helps.

https://www.onsemi.com/pub/Collateral/AN-118.pdfJP.pdf

 

http://ltwiki.org/LTspiceHelp/LTspiceHelp/A_Special_functions_.htm -- "The Schmitt trigger devices have similar output characteristics as the gates. Their trip points are specified with instance parameters Vt and Vh. The low trip point is Vt-Vh and the high trip point is Vt+Vh.". . . At SpiceModel [ SCHMITT ] , at SpiceLine [ Vhigh=5 Vlow=0 td=6n vt=2.1 vh=0.44 ]

 

Well i worked on this a bit does this look like a good circuit