First off, do a strengths/weaknesses/opportunities/threats analysis of your cycling and you goals.
Theres no one true way for anything, but if your primary goal is to cycle faster its likely 8h of cycling will get you there quicker.
To decide if strength is a weakness, have a look at Chad’s strength targets for cyclists.
Then weigh it up against all your other challenges; consistency, sleep, nutrition…and so on. If youre missing 20% of a 5h trainjng week, increasing it to 8h may not be effextive.
Remember that strength training is a secondary, supporting activity to cycling, you absolutely cannot swap an hour if ine for an hour of the other and expect equivalent benefits.