Picking up short calls is a smart gambit, IF you're close enough and they're fat in your seat. The number of SC's published tends to vary a bit, but is much higher than it was in years past. And, the number of times used on SC can vary as well. On my last fleet, I flew (or deadheaded to cover) on a fair amount of SC's. My current fleet, not so much.

As far as a budget, I'd say its a no brainer if you're bidding reserve intentionally. If your BES reserve life goes to crap, you can always bid a line and increase (typically) your pay. But the guy who bids up a seat and plans on steadily receiving 78-79 hours pay on reserve might be disappointed.

And if they're short in your BES, you might end up working like a sled dog just to make guarantee.

Reserve can be a bit of a crapshoot. It can also be pretty decent, depending on your zip code and what's going on with the airline as it shuffles & staffs the metal.