The Blues boss will this summer again use the loan market to bolster his Fratton Park squad.
Yet Cowley is wary of recruiting promising youngsters who do not possess first-team experience.
Gavin Bazunu, Hayden Carter and George Hirst have flourished at Pompey this season, yet all previously featured elsewhere on loan.
Bazunu turned out 32 times for Rochdale last term, while Carter made 24 appearances at Burton in the second half of the campaign, and Hirst was at Rotherham for 32 games.
In contrast, Miguel Azeez and Gassan Ahadme struggled to shine during what represented their first time away from parent clubs.
And Cowley admits he may prioritise both youth and experience in the loan market.
He told The News: ‘With Gavin and Hayden, these are young players on the way up, with both having previous loans at this level and done relatively well before.
‘As a consequence, straight away you have context which can help make decisions.
‘If you are looking at a young player that hasn’t been out on loan before and the only context is under-23s football, it can be harder for you to gauge how they are going to cope with the different challenges that League One football provides.
‘You can argue Miguel and Gassan didn’t work – and certainly they didn’t have League One experience having not played at these levels before.
‘Having lived these levels for the first time, they will be better for the experience. They will have benefited as players, their parent clubs would also have benefited – but we didn’t.
‘Gassan lived it in the first half of the season with us, he got to understand what it requires, the demands of it and how to adapt your game to be able to perform consistently well.
‘Whereas Hayden and Gavin had both lived it and it was pretty clear both had done reasonably well, are on an upward curve, and really good characters.’
Ahadme’s loan was cancelled in January by Norwich and subsequently sold him to Burton.
He has since netted twice in 12 matches, although racked up just 28 minutes of first-team action on the last seven occasions he has been included in the match-day squad.
Meanwhile, Azeez was recalled by Arsenal in January, with the Premier League club unhappy over just 10 appearances.
He has subsequently been on the Gunners’ bench in their last two league games – Southampton and Brighton – although wasn’t called upon in successive defeats.
Cowley added: ‘That’s never to say we won’t take a first-time loan, because sometimes, if you don’t, then they go beyond you by the time you get to the second loan.
‘We also know that first-time loans also come cheaper, so all these things are in the pot. This is why there are no hard and fast rules with recruitment.’
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