Why do some people believe different days of the week? Ive never heard of that,it's always been good Friday and Easter Sunday as far as I can remember. But I must admit it has that squeezed into a weekend type of feeling about it to me. I wish we celebrated the resurrection of Jesus with the same vigour that the world claims to celebrate Christmas with. I don't know one decent Easter hymn.
One reason that many people do not know that there are several competing theories as to the timeline of Jesus' last week goes far back to the early centuries after Christ - the Quartodeciman controversy.
In brief, Christians early on had various customs about 'when' they celebrated Jesus' death and resurrection. Christians in Jerusalem and Asia, such as the disciples of the Apostle John, tended to celebrate Jesus' death and Ressurection (with footwashing and communion) at sundown on Nissan 14th - Passover.
(Quartodecimen means '14th')
Christian in Rome and the surrounding regions usually kept the celebration on the Sunday after Passover. Passover was not fixed to a specific day of the week, but rather a specific date - so there was variation in the number of days between these two celebrations.
Part of this differing custom was a difference in focus. The Jewish converts usually highlighted Christ's atonement by His death, while the Gentile converts, having no history of celebrating Passover, tended to highlight the Ressurection.
This difference in custom was causing friction in the church in the second century, to the point where Polycarp, the bishop of Smyrna, and Anicetus, the bishop of Rome, met to try and convince each other of their own preferred 'best day' in 155 AD. Polycarp promoted Nisan 14, while Anicetus promoted the Sunday after Passover. After discussing it, they agreed to 'live in peace.' They took communion together, upholding the scriptural principle that personal customs do not trump unity in the spirit (Col 2:16-17, Rom 14:5-6)
"Anicetus conceded the administration of the eucharist in the church to Polycarp, manifestly as a mark of respect. And they parted from each other in peace, both those who observed, and those who did not, maintaining the peace of the whole church." (Irenaeus, writing several decades later to Pope Victor)
Unfortunately, this peace did not last. A few decades later, near the end of the second century, Pope Victor, did not wish to 'live in peace' with those of differing customs, despite the pleading of Irenaeus. several synods and conferences had been convened, with their decrees sent out in letters to all Christians, that "never on any day other than the Lord's Day (the Sunday after Passover) should the mystery of the Lord's resurrection from the dead be celebrated, and on that day alone we should observe the end of the Paschal fast."
Polycarp's response was, "We observe the exact day; neither adding, nor taking away. For in Asia also great lights have fallen asleep, which shall rise again on the day of the Lord's coming...All these observed the fourteenth day of the passover according to the Gospel, deviating in no respect, but following the rule of faith. And I also, Polycrates, the least of you all, do according to the tradition of my relatives, some of whom I have closely followed. For seven of my relatives were bishops; and I am the eighth. And my relatives always observed the day when the people put away the leaven."
Pope Victor then attempted to 'excommunicate' Polycarp and all those who followed the Quartodeciman custom. Fortunately other leaders in the church of the time, like Irenaeus, opposed this act of Victor's and did not treat his 'excommunication' as valid, and Victor eventually relented. Yet it still had an effect - the quartodecimens were losing favor within the larger Christian community and facing mounting pressure.
In 325 AD, the Nicene Council rebuked the Quartodecimen position. It's not hard to understand why given the nature of man; Jewish Christians had become a small, persecuted minority in the church by that point, unlike the early days of the gospel where Jewish converts were closer in number to gentile converts, even the majority in some areas. Jewish customs, because they were the minority, were viewed as 'divisive' and accused of being a return to the law.
Following the rebuke of the Nicene Council, Emperor Constantine went a step further, banning the celebration on 14 Nissan entirely, and ordered active persecution against the Quartodecimens. Constantine also declared the Sunday after the first full moon after the spring equinox (not the Sunday after Passover) to be the one and only 'official' date for the Paschal celebration.
The Quartodecimen practice quickly died out after that, albeit with some holdouts who were persecuted by bishops Crystosostom and Nestorius.
All that to say - Constantine 'set the date,' those of differing customs either caved or were pushed out of the church, and the Catholic church unified around the date that had been set. Further liturgy and tradition sprung up around that. Palm Sunday, for example, had its start in 8th century Italian Catholic tradition - and then more explanations and 'history' were added to support that. (Despite that scripture actually gives more evidence that it could not have been on a Sunday than that it was - for example, no one would be cooking a dinner on the Sabbath (serving, maybe, but never making Jn 21:2).
It's not surprising, then, that the 'official' timeline of the Catholic church is the one most people are aware of or the only one they have heard about. It doesn't help that the events of Jesus' last days are often presented in the stylized tradition of Holy Week, and not always with a thorough examination of scripture.