Resale tickets for centre after 4.00 are often debenture seats, little to right of van court Royal box end. Nice seats for not much money.
When I entertain at WO I usually have to leave at four - it is a working day. If I go under my own steam I leave after the last ball is played, say 9.20.
Ideal scenario is a backlog of matches, unexpected rain and a late centre court match under the roof. Start queuing at 12.00 and you will be in between 4.00 and 6.00. Then queue again for show court returns - two queues, one for centre and one for eithe one or two. 30 mins max.
Or just wander around the outside courts.
Queues are longer than I have ever seen before, so be prepared for a long day. you can go early ie 7.00. People camping get woken at 6.00 and are queuing by 6.30.
You get a card with a number so you don't have to stand in the line all day, but you can't disappear for ages either.