The old arch-reformer Pio XII more or less abolished Lent as a real penitential season in Italy by removing the obligation to follow the ancient fasting obligations during the war. Popes can let genies out of bottles but can't put them back in again.
In Venice the season of Carnival is nowadays an immense tourist draw, the too wealthy and vulgar will hire extravagant costumes and masks and attend the balls at some canal-side palace. I remember meeting Nigel and Caroline dressed as characters from a Canaletto picture coming out of the eerie Venetian fog on the day before Shrove Tueday, it was ghostly. Carnival is today as it was in the 18th century an occasion of excess. Then certain crimes committed wearing a doto were presumed no crime at all, because of lack of certain identity. Churchmen when not taking part in them railed against them.
Septagesima marked the beginning of Carnival though during the eighteenth century the partying and merrymaking took up most of the year, however it stopped for Lent as the bell of St Mark's tolled midnight and Ash Wednesday and Lent began.
The weeks before Lent began in the East and West were a gradual introduction to Lent. In the East the Lenten discipline bore down like a tightening screw getting more and more demanding until by Holy Week the faithful were living virtually on bread and water. In the West Lenten fasting in all its severity was from Ash Wednesday and meant an absence from meat and dairy products, and any practical pleasures from feasting to theatre. The period from Septagesima was a rather more positive time than Lent proper. People were getting rid of those things which were not to be consumed during Lent and partying, hence the idea the of Carnival. As in Venice it could be a great source of sinfulness but it could also be a way of preparing for Lent and the Paschal Mystery. In England Shrovetide was time to prepare for Lent, a time for Confession and reconciliation, for alms-giving and but most especially of hospitality. This pre-Lent period was a time to strengthen and make new friendships, for the wealthy to distribute the food and alms and welcome the less fortunate into the homes and show practical Charity before embarking on the self denying practices of Lent. In practice the Gesima season was sharply divided by Ash Wednesday between the period of practical charity to one's neighbour and interior contemplation of Christ and Passion. A good Lent is one that is planned, and begun in acts of real charity, the period from Septagesima is the time for this.
I suspect those decadent baroque masks worn traditionally in Venice during Carnival partying were originally the masks worn by the pious confraternities whilst they undertook acts of charity and piety.