Martin, your maximum bid is not placed, just the amount necessary to win the auction. So if you have a $52 max bid on an item that is currently at $26, and NO ONE ELSE BIDS HIGHER, you would win the auction for $27. You would also pay AS its few cents as a fee.
Just remember that you have no way to know what the true max bid is. The high bid may show up as $26, but that bidder may have actually have a high bid of $42. This is how eBay works. If no one else bid, then he would win for $26. If you show up (via AS or otherwise) at the last seconds for $52, then you would win for $43, which was just enough to beat the other bidder. If it turns out that the bidder's actual max is $76, then he will win for $53, enough to beat your max. But since you waited until the closing seconds, neither of you would know this until the auction ends. But at least you would have made him pay for that object that he wanted more than you.
Just decide in advance how much is the absolute max you will want to pay for an item, set your AS bid, and that's all you need to do, except wait for the auction to end. I find that I win 95% of my auctions through AS, most for considerably less than my max, but it also depends on what you seek and how popular the items are. Mine are mostly small and inexpensive goodies.
I NEVER bid manually on eBay, except in the very rare case that I wish to eliminate an unsually high BUY IT NOW price that I am unwilling to pay. Most of the time I just use the BUY IT NOW feature, if that option is offered and it is not far beyond what I would be willing to bid. Good luck to you and welcome to AS.