You don't need to rush the event gacha. The full clear is possible quite easily (1 week should be enough).

The total sake needed is : 88500 sake (=100*(10+25+40+55+70+85+100+100+100+100+100+100))

If you can only spam the bonus stage 6 times and only do E-1,
the sake/stamina ratio is: 24.7 sake/sta
so you only need 3593 sta (~7.5 days)

If you can spam the bonus stage 16 times and do E-4,
the sake/stamina ratio is: 61.45 sake/sta
so you only need 1441 sta (~3 days)