Rules of thumb:
If it touches a vehicle it gets laminated.
If it goes outside it gets laminated (unless VERY temporary yard sign) even then, it's harder to mount to substrate when thin and gooey.
If it's a banner it does NOT get laminated (because I don't want my customers thinking or expecting banners to last forever or be substitutes for permanent signage)
LOL 15 years ago when I was in So California we used to liquid lam all our true solvent printed banners...but we also used to get $8.25 a sq.ft. for them too. (those days are long gone)
If it is for indoors.....
Wall decals on fabric do not get laminated
Floor decals absolutely need laminated with non-slip lam
Roll up banner stands no lam (too thick and grabby)
X-frame stands no lam on banner
signage usually gets laminated due to ease of mounting, professional look, scratch resistance, fade resistance if near windows etc