To my knowledge, OD minimally trains HA and DR (about 20 training session for a single pop, assuming 18 year old prospect, height 201cm + lvl5 trainer). PA trains HA and DR at a rate of 6-7 sessions per pop for an 18 yr old.
OD has an elastic effect on PA and HA(i also believe on JR but some people contest this). DR pulls heavily OD and a bit less on HA. HA has an elastic effect on PA as well. But PA itself has no elastic effect on any skill.
For a defensive player I would train:
2 full seasons 1v1 forwards
2 seasons OD
1 season ID
1 season SB
2 seasons RB
1 season ID
1 season SB
2 seasons PA
I'd only recommend this type of training if all of your players are defensively oriented and also having good passing skills.
Otherwise:
1 season1v1 forwards
1 season OD
Half a season 1v1 forwards, half a season JS forwards
1 season ID
1 season RB
1 season SB
1 season IS
1 season ID
1 season IS
2-3 seasons PA