If you check out the Commentaries, you will see that the 50 kinds of arising-passing are for Arahants. For others who don’t know them, they are 5 kinds of arising of the body (arising of the avijjā & saṅkhāra & kamma in the next life, āhāra (food) during this life, and nibbatti (simply arising) in the present moment) + 5 kinds of passing away of the body (the three as before arising in the past life and passed upon birth; passing away of āhāra during this life; and vipariṇāma (passing away in the present moment). These ten (5 arising & 5 passing) are observed in the body, feelings, perceptions, intentions, and consciousness (i.e., in all the five aggregates) → (5+5) * 5 = 50.
The Commentaries explain that the Arahants can see the arising of avijjā, taṇhā, and kamma in their previous life (as remembering their past lives) and (for our topic, more importantly) the no-more arising of their avijjā-taṇhā-kamma in the Arahants’ next life because they are Arahants, free from rebirth.
So, those who have udayabbaya ñāṇa must have already been liberated from the next birth so that they can see that their avijjā-taṇhā-kamma of their next life won’t arise anymore simply because they are clear about their Arahanthood. Here taṇhā & kamma refer to saṅkhāra, the second point of the Dependent Origination. Here I need to note that the avijjā & saṅkhāra (taṇhā & kamma) points of the Dependent Origination are understood as happening in a previous life, as conditions for rebirth (rebirth then starts by the “viññāṇa” point of the Dependent Origination).
Interestingly, the Paṭisambhidāmagga is the only Mūḷa Pāḷi text that discusses the vipassanā ñāṇas systematically. In the Commentaries, we will find the vipassanã ñāṇas discussed at length by Visuddhimagga only, where we get all 16 levels.
I wonder if Visuddhimagga is actually not just the first, but actually, the only Pāḷi text that discusses Vipassanā ñāṇas for puthujjanas (non-Enlightened persons) & sekhas (Enlightened non-Arahants). Be as it may, the 16 levels of vipassanā ñāṇa are rooted in the original Pāḷi text of Rathavinīta Sutta, so I personally like them. Note, however, that you can “jump over” some stages between 5 & 11, and some go so fast that you are not even expected to notice, such as magga and phala! Or so I have learned from the great Burmese masters.
The great sayadaw Ashin Paṇḍābhivaṃsa explains in his book “Paṭipattikkama Ṭīkā” (“The Subcommentary about (Meditation) Practice”), p. 369, that Muñcitukamyatāñāṇa, Paṭisaṅkhāñāṇa, Saṅkhārupekkhāñāṇa are different as words, but they are the same in their meaning:
“မုဉ္စိတုကမျတာဉာဏ်၊ ပဋိသင်္ခါဉာဏ်၊ သင်္ခါရုပေက္ခါဉာဏ် ဟူသော နာမည် ပညတ်တို့သည်ကား သဒ္ဒါမျှသာထူး၍ အတ္ထကား တူကြလေသည်။”
And then, on page 370, he adds that Vipassanā ñāṇas are only the way how nature is. No one can experience them one after another.
“ဤသို့ ပြဆိုအပ်ပြီးသော အဆင့်ဆင့်သော ဉာဏ်စဉ်တို့သည်ကား ပုဂ္ဂလကိစ္စနှင့် မရောမယှက်ဓမ္မကိစ္စ သက်သက်မျှသာ ဖြစ်လေသည်။ ထို့ကြောင့် တစ်ခုသောဉာဏ်ဆင့်မှ သည်တစ်ခုသော ဉာဏ်အဆင့်သို့ ရောက်အောင် ပုဂ္ဂိုလ်အနေအားဖြင့် ဘယ်သူမှ မစွမ်းဆောင်နိုင်ကြချေ။”
The meditation master “Vipassanā Pāragū,” apparently a senior student of Ledi Sayadaw, wrote in his “Vipassanā Hsayar Pshit Thintan, Vipassanā Pāragū Kyam” (“The course on becoming a Vipassanā master, the book of those accomplished in Vipassanā”) on page 82 that because gotrabhū, magga, and phala ñāṇas take altogether only around 5 mind-moments they may feel indistinguishable, as a single, unified experience of mind directed toward Nibbāna.
“ဤဂေါတြဘူ, မဂ်ဖိုလ်, ဉာဏ်သုံးပါးသည်လည်း စိတ္တက္ခဏ လေးကြိမ် ငါးကြိမ်မျှသာ ကြာရသောကြောင့် ဘယ်ဉာဏ်က ဘယ်လို နေသည်ဟု ယောဂီ၏ စိတ်၌ မခွဲခြားတတ်ပေ။ သို့ရာတွင် ထိုဉာဏ် သုံးပါးမှာ လောကြီးကို အာရုံ မပြုဘဲ နိဗ္ဗာန်ကို အာရုံပြုတာချင်းကလည်းတူ၊ တစ်ဆက်တည်းကလည်း ဖြစ်ကြရ၍ သုံးပါးစလုံးကို တစ်ပေါင်းတည်း ပြု၍မူကား သိသာလှပါ၏။”
More commonly, however, students happen to stay in the phalañāṇa for a number of minutes. According to the Commentarial explanation, phala ñāṇa takes two mind-moments. Vipassanā Pāragū explains that the additional moments of phalañāṇa are javana moments.
ဤသို့ ဂေါတြဘူ, မဂ်, ဖိုလ်, ဖိုလ် ဟူသော စိတ္တက္ခဏလေးငါးချက်ဖြင့် နိဗ္ဗာန်ကို မျက်မှောက်ပြုသွားရင်း ဖိုလ်ဇောတွေ ဆက်၍ မိနစ်ပေါင်း အတော်ကြာအောင် ဆက်၍ ကျသွားသော ယောဂီများမှာမူ ပို၍ ထင်ရှားလှပါ၏။"
Abhidhammatthasaṅgaha lists only ten kinds of Vipassanā Ñāṇa (insight knowledges) :
“Sammasanañāṇaṃ udayabbayañāṇaṃ bhaṅgañāṇaṃ bhayañāṇaṃ ādīnavañāṇaṃ nibbidāñāṇaṃ muccitukamyatāñāṇaṃ paṭisaṅkhāñāṇaṃ saṅkhārupekkhāñāṇaṃ anulomañāṇañceti dasa vipassanāñāṇāni.” (Abhidhammatthasaṅgaha - 9. Kammaṭṭhānaparicchedo - Vipassanākammaṭṭhānaṃ - Visuddhibhedo - par. 46, MM Abhs 63)