One wears upanayana on ear during excretion (urine/stools). Women have third level of excretion (menstruation). Difficult wear janeu on ear for 4-5 days at a stretch.
Post that, one would need discard old & take up new janeu in new month.
One has to sit bare chested in front on rising sun facing and hold up upavīta then wear it and do gāyatri japa
One may even do japa after wearing clothes (no sewn clothes - only sari, no any other garments - inner or outer)
Point is - only one who has a Pvt puja room May do it, provided she somehow uncomfortably tackles the janeu management around ear problem for four days.
no one is asking woman to be nude but it needs that dispassion. And with that sort of dispassion, one’s married life “may” suffer
That time is gone for 1200 years at least.
Until that time, all this is theoretically useless topic. One may wear three threads - but it isn’t janeu.
It will greatly accelerate my moksha. 😂
Many people don’t know but for woman, vivāha is her upanayana. She gets a janeu of her own. Just that her husband wears it for her and does all the maintenance.
But on adhidaivik or pāralaukika front - married woman gets a free ride on most things
Has to do close to nothing if husband is doing all his things properly. Gets all the fruit automatically