Back when, consecutive numbers were genuinely rare, only a few people collected and even fewer were tucking away runs of notes. Not so, today. Consecutive numbers are not common, but certainly not difficult to locate in quantity with modern issues.
Unless they are in pristine Gem UNC 67 condition, consecutive numbers don't really do much for value, seeing as how you need to pony up double or triple the price of a single to get them.
Around 5% to 10% for a premium, but condition is everything. Some folks do collect notes in threes, for that album page with three slots.
If you can afford to do so, tuck a few pairs or threes away for the long term, the population of sequential notes only gets smaller, never larger, once they hit circulation and the market.