@kungfufool45Florida Friends series by Dual Writer has some sequences of 2-3 novels featuring the same main character. They get a bit slice-of-life which may be tedious at times, but little angst.
Lazlong's Wagons Ho! and its sequel are pretty long.
A Fresh Start by rlfj. Has its ups and downs, but most of the time the MC is successful.
A New Past by Charlie Foxtrot is similar -- it's a do-over, with its share of painful experiences, but the main character is (very) successful, in the end. More SF elements than A Fresh Start.
"A Golfer's Dream" series by The Caddy. Coming of age/sports.
"Playing the Game" series by Rev. Cotton Mather is another coming of age/sports series, but it had quite a bit of (annoying to me) angst at the end; despite happy ending.
Oyster50 has several sequences within his "Smart Girls" universe that feature the same (male) protagonist. However, the most likable characters are usually the (young, brilliant) eponymous girls, who become love interests of each respective MC.
Aroslav has a couple of very long sagas, of generally likable and successful heroes, but they do go through a lot of angst (I would consider them emo, but they do overcome emotional challenges in the end).
Daze in the Valley by Jay Cantrell. Much of the novel is about the porn industry which may be off-putting, but the main character is likable and successful. Very loosely tied to a couple of his other novels.
The Defenceman by Cold Creek. A coming of age/sports novel; which is fun in the beginning, but get tedious and angsty towards the end, so perhaps not the best choice. The MC has a lot of unlikely encounters -- much like the Richard Jackson saga; except I think Banadin/Ed Nelson had a better approach using humor.