My selection is the one on the left.

Betting to fixed Liability is the safest way to lay because its the closest version of level stakes betting as in win only betting.

If one wishes to place the same amount on each selections , one has to know what the max acceptable price one is going to accept .
Once we know what the max price is , we now convert this to fractional odds & divide this figure into say 5,7 or 10% of bank & this becomes your fixed outlay amount.

Example.
Max odds 9/1
10% Bank Liability
$1,000 Bank.

$100 / 9 = $11.11 flat Lay bet on all selections regardless of price up to $10.00.
With this approach , we are assuming the shorter priced runners will win more often than the longer priced runners, therefore reduced Liability exposure.

The lay method I currently use is now on success number 132 in a row , using a program I have written.
I use Variable Stakes Liability to Bank set at 33% of bank.

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Cheers.