I wouldnt but if your recording the results trial both approaches to see..
Its all good fun and a learning experience all round.
Generally horses are a creature of habit and they,ll do what they,ve previously done.
i.e if they generally fail 1st or 2nd up then that pattern will continue
If you use a quality racing paper like Sportsman and observe the racing patterns of various horses (say in the top 4or 6 of the bookies OPENING market)its a very good way of PROFILING horses patterns.
i.e
distance preferences
track condition preferences
how long it takes to reach peak fitness
weight carried successfully or not /weight rises Fron LIMIT weight
etc etc
you then gain a far greater knowledge of horse racing than any system could give you although some systems actually do work if based on logic which unfortunately most commercial systems dont.

cheers.
darky