When washing white linen sheets, should pour some bleach into the washer each time? why? how depends?
Be aware that some white fabrics are actually DYED white. So when you use bleach, the bleach lifts out the dye and leaves the fabric its original undyed colour, usually a pale yellow or even grey.
the bleach will rinse out, just like the detergent does. Are they pure linen? If so, a little bleach is great. If there is polyester in the sheets, that will turn yellow from the bleach.
Spock (rhp): suggestion
suggestion: use OxyClean or other non-chlorine bleach. Put recommended amount in the washer and fill with water, adding whites when about half full. STOP the washer about two or three minutes after it begins to agitate. Then wait 30 to 45 minutes, with shirts in the soapy water, and finish the cycle. Dry normally. This soaking in non-chlorine bleach process will prevent or even reverse yellowing. It works for very light colors as well [those light blues, pale pinks, and light yellows the designers think look good on us].
Use vinegar once in awhile.