Do you have to swim on a team to improve?

Technically I swim with a team. I am in the pool the same time as other Masters swimmers. However, 90+% of my workout is done on my own pace and different time than the other swimmers. Much of this is because I start 30 minutes later than the 6 a.m. crowd, and 30 minutes earlier than the 7 a.m. crowd. Since I am unwilling to get up even earlier, or get to work later, that's how it works out. And my "team" is loosely structure which means we can swim whenever. Most of the time I use between half and three quarters of the planned workout. I am 50, have been swimming for 4 years now and doing PBs. Like Fortress - I have a hard time with aerobic sets. One - I don't like them anyways. Two - it is hard to swim them hard relying purely on my motivation (or lack of). But I most like to have people to swim with on sprints - because it is more like racing.

Technically I swim with a team. I am in the pool the same time as other Masters swimmers. However, 90+% of my workout is done on my own pace and different time than the other swimmers. Much of this is because I start 30 minutes later than the 6 a.m. crowd, and 30 minutes earlier than the 7 a.m. crowd. Since I am unwilling to get up even earlier, or get to work later, that's how it works out. And my "team" is loosely structure which means we can swim whenever. Most of the time I use between half and three quarters of the planned workout. I am 50, have been swimming for 4 years now and doing PBs. Like Fortress - I have a hard time with aerobic sets. One - I don't like them anyways. Two - it is hard to swim them hard relying purely on my motivation (or lack of). But I most like to have people to swim with on sprints - because it is more like racing.