Mass scrolling

What would be the best/cheapest way to go about doing it? I'm shooting for 6/7 20%s with 1 slot left on a Maple weapon, and I'm unsure whether to spam scrolls on single bases until it dies or make tons of 1/7 bases and progressively scroll 2/7 bases from there and so on. From previous experience with more achievable goals (2 30%s or so), it seemed that the first method worked fine, but for this I'm not so sure it will. Also unsure of how many bases and scrolls I should expect to use before achieving my goal, I'd usually go for the standard 5^6 bases but again from previous experience this seems way too high.

Any other general tips on mass scrolling are welcome.

It depends on whether partial success has any value to you.

For example, if after everything you tried, the best you managed was 4 scrolls passing, would you use that? Scroll the rest with 50's/60's with or without whites/pam's? Or would that be not as good as what you currently have?

If you absolutely must pass 6 for the weapon to be of any use to you, might as well just spam them on single bases.

If you think you might later regret not holding on to that one lucky streak of 4, get at least two items with 1 scroll passed before you try a second scroll on one of them. Once you have one 1 and one 2, try a second on the 1. Only after you have two 2's, try a third on one of them. And so on. Always make sure you do not risk your "high water mark", the best you've managed so far. Only risk the second-best or equal.

When you are out of blanks or out of scrolls, examine what you have left - which is necessarily the best - and decide on your future course of action.

That's the way I'd do it, anyway.