Hi and welcome,
on routes where you have exclusivity, you'd typically want to supply roughly 90% of the demand, so you can increase prices while maintaining a very high LF.
If, on these routes you supply 100% of the demand and have below 90% LF, that's most likely because your RI is not yet at 90-100, so just wait a bit longer. Another possibility is that you increased prices too much - AWS passengers prefer not to fly that to fly fo too much money.
On routes with competition, the ideal would be to share it so that the overall supply is roughly 90% of the demand as well. However it wouldn't be called competition if one wouldn't try to take the lead and discourage the others from flying it.
Basically, the demand gets fragmented more or less equally between the number of flights. And unless you want the other guy dead (which btw would be very costly for you), you want to keep your LF between 70 and 90%. So if the route has 1000 demand and the current supply is 600 amongst 5 flights, you can add 6 or even 7 flights.
On the other hand, if the demand is 1000 with 900 supply split amongst 16 flights, you barely want to add 2 flights.
Hope this helps.